Beispiel #1
0
 def __init__(self, truth_problem, **kwargs):
     # Call the parent initialization
     DifferentialProblemReductionMethod_DerivedClass.__init__(self, truth_problem, **kwargs)
     
     # Declare a GS object
     self.GS = None # GramSchmidt (for problems with one component) or dict of GramSchmidt (for problem with several components)
     # I/O
     self.folder["snapshots"] = os.path.join(self.folder_prefix, "snapshots")
     self.folder["post_processing"] = os.path.join(self.folder_prefix, "post_processing")
     self.greedy_selected_parameters = GreedySelectedParametersList()
     self.greedy_error_estimators = GreedyErrorEstimatorsList()
     self.label = "RB"
    def __init__(self, SCM_approximation, folder_prefix):
        # Call the parent initialization
        ReductionMethod.__init__(self, folder_prefix)

        # $$ OFFLINE DATA STRUCTURES $$ #
        # High fidelity problem
        self.SCM_approximation = SCM_approximation
        # I/O
        self.folder["post_processing"] = os.path.join(self.folder_prefix,
                                                      "post_processing")
        self.greedy_selected_parameters = SCM_approximation.greedy_selected_parameters
        self.greedy_error_estimators = GreedyErrorEstimatorsList()
Beispiel #3
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 def __init__(self, SCM_approximation, folder_prefix):
     # Call the parent initialization
     ReductionMethod.__init__(self, folder_prefix)
     
     # $$ OFFLINE DATA STRUCTURES $$ #
     # High fidelity problem
     self.SCM_approximation = SCM_approximation
     # I/O
     self.folder["post_processing"] = os.path.join(self.folder_prefix, "post_processing")
     self.greedy_selected_parameters = SCM_approximation.greedy_selected_parameters
     self.greedy_error_estimators = GreedyErrorEstimatorsList()
     
     # Get data that were temporarily store in the SCM_approximation
     self.bounding_box_minimum_eigensolver_parameters = self.SCM_approximation._input_storage_for_SCM_reduction["bounding_box_minimum_eigensolver_parameters"]
     self.bounding_box_maximum_eigensolver_parameters = self.SCM_approximation._input_storage_for_SCM_reduction["bounding_box_maximum_eigensolver_parameters"]
     del self.SCM_approximation._input_storage_for_SCM_reduction
Beispiel #4
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 def __init__(self, EIM_approximation):
     # Call the parent initialization
     ReductionMethod.__init__(self, EIM_approximation.folder_prefix)
     
     # $$ OFFLINE DATA STRUCTURES $$ #
     # High fidelity problem
     self.EIM_approximation = EIM_approximation
     # Declare a new container to store the snapshots
     self.snapshots_container = self.EIM_approximation.parametrized_expression.create_snapshots_container()
     self._training_set_parameters_to_snapshots_container_index = dict()
     # I/O
     self.folder["snapshots"] = os.path.join(self.folder_prefix, "snapshots")
     self.folder["post_processing"] = os.path.join(self.folder_prefix, "post_processing")
     self.greedy_selected_parameters = GreedySelectedParametersList()
     self.greedy_errors = GreedyErrorEstimatorsList()
     #
     # By default set a tolerance slightly larger than zero, in order to
     # stop greedy iterations in trivial cases by default
     self.tol = 1e-15
Beispiel #5
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class EIMApproximationReductionMethod(ReductionMethod):
    
    # Default initialization of members
    def __init__(self, EIM_approximation):
        # Call the parent initialization
        ReductionMethod.__init__(self, EIM_approximation.folder_prefix)
        
        # $$ OFFLINE DATA STRUCTURES $$ #
        # High fidelity problem
        self.EIM_approximation = EIM_approximation
        # Declare a new container to store the snapshots
        self.snapshots_container = self.EIM_approximation.parametrized_expression.create_snapshots_container()
        self._training_set_parameters_to_snapshots_container_index = dict()
        # I/O
        self.folder["snapshots"] = os.path.join(self.folder_prefix, "snapshots")
        self.folder["post_processing"] = os.path.join(self.folder_prefix, "post_processing")
        self.greedy_selected_parameters = GreedySelectedParametersList()
        self.greedy_errors = GreedyErrorEstimatorsList()
        #
        # By default set a tolerance slightly larger than zero, in order to
        # stop greedy iterations in trivial cases by default
        self.tol = 1e-15
    
    def initialize_training_set(self, ntrain, enable_import=True, sampling=None, **kwargs):
        import_successful = ReductionMethod.initialize_training_set(self, self.EIM_approximation.mu_range, ntrain, enable_import, sampling, **kwargs)
        # Since exact evaluation is required, we cannot use a distributed training set
        self.training_set.distributed_max = False
        # Also initialize the map from parameter values to snapshots container index
        self._training_set_parameters_to_snapshots_container_index = dict((mu, mu_index) for (mu_index, mu) in enumerate(self.training_set))
        return import_successful
        
    def initialize_testing_set(self, ntest, enable_import=False, sampling=None, **kwargs):
        return ReductionMethod.initialize_testing_set(self, self.EIM_approximation.mu_range, ntest, enable_import, sampling, **kwargs)
    
    # Perform the offline phase of EIM
    def offline(self):
        need_to_do_offline_stage = self._init_offline()
        if need_to_do_offline_stage:
            self._offline()
        self._finalize_offline()
        return self.EIM_approximation
        
    # Initialize data structures required for the offline phase
    def _init_offline(self):
        # Prepare folders and init EIM approximation
        all_folders = Folders()
        all_folders.update(self.folder)
        all_folders.update(self.EIM_approximation.folder)
        all_folders.pop("testing_set") # this is required only in the error/speedup analysis
        all_folders.pop("error_analysis") # this is required only in the error analysis
        all_folders.pop("speedup_analysis") # this is required only in the speedup analysis
        at_least_one_folder_created = all_folders.create()
        if not at_least_one_folder_created:
            return False # offline construction should be skipped, since data are already available
        else:
            self.EIM_approximation.init("offline")
            return True # offline construction should be carried out
        
    def _offline(self):
        interpolation_method_name = self.EIM_approximation.parametrized_expression.interpolation_method_name()
        description = self.EIM_approximation.parametrized_expression.description()
        
        # Evaluate the parametrized expression for all parameters in the training set
        print(TextBox(interpolation_method_name + " preprocessing phase begins for" + "\n" + "\n".join(description), fill="="))
        print("")
        
        for (mu_index, mu) in enumerate(self.training_set):
            print(TextLine(interpolation_method_name + " " + str(mu_index), fill=":"))
            
            self.EIM_approximation.set_mu(mu)
            
            print("evaluate parametrized expression at mu =", mu)
            self.EIM_approximation.evaluate_parametrized_expression()
            self.EIM_approximation.export_solution(self.folder["snapshots"], "truth_" + str(mu_index))
            
            print("add to snapshots")
            self.add_to_snapshots(self.EIM_approximation.snapshot)

            print("")
            
        # If basis generation is POD, compute the first POD modes of the snapshots
        if self.EIM_approximation.basis_generation == "POD":
            print("compute basis")
            N_POD = self.compute_basis_POD()
            print("")
        
        print(TextBox(interpolation_method_name + " preprocessing phase ends for" + "\n" + "\n".join(description), fill="="))
        print("")
        
        print(TextBox(interpolation_method_name + " offline phase begins for" + "\n" + "\n".join(description), fill="="))
        print("")
        
        if self.EIM_approximation.basis_generation == "Greedy":
            # Arbitrarily start from the first parameter in the training set
            self.EIM_approximation.set_mu(self.training_set[0])
            
            # Carry out greedy selection
            relative_error_max = 2.*self.tol
            while self.EIM_approximation.N < self.Nmax and relative_error_max >= self.tol:
                print(TextLine(interpolation_method_name + " N = " + str(self.EIM_approximation.N), fill=":"))
                
                self._print_greedy_interpolation_solve_message()
                self.EIM_approximation.solve()
                
                print("compute and locate maximum interpolation error")
                self.EIM_approximation.snapshot = self.load_snapshot()
                (error, maximum_error, maximum_location) = self.EIM_approximation.compute_maximum_interpolation_error()
                
                print("update locations with", maximum_location)
                self.update_interpolation_locations(maximum_location)
                
                print("update basis")
                self.update_basis_greedy(error, maximum_error)
                
                print("update interpolation matrix")
                self.update_interpolation_matrix()
                
                (error_max, relative_error_max) = self.greedy()
                print("maximum interpolation error =", error_max)
                print("maximum interpolation relative error =", relative_error_max)
                
                print("")
        else:
            while self.EIM_approximation.N < N_POD:
                print(TextLine(interpolation_method_name + " N = " + str(self.EIM_approximation.N), fill=":"))
            
                print("solve interpolation for basis number", self.EIM_approximation.N)
                self.EIM_approximation._solve(self.EIM_approximation.basis_functions[self.EIM_approximation.N])
                
                print("compute and locate maximum interpolation error")
                self.EIM_approximation.snapshot = self.EIM_approximation.basis_functions[self.EIM_approximation.N]
                (error, maximum_error, maximum_location) = self.EIM_approximation.compute_maximum_interpolation_error()
                
                print("update locations with", maximum_location)
                self.update_interpolation_locations(maximum_location)
                
                self.EIM_approximation.N += 1
                
                print("update interpolation matrix")
                self.update_interpolation_matrix()
                
                print("")
                
        print(TextBox(interpolation_method_name + " offline phase ends for" + "\n" + "\n".join(description), fill="="))
        print("")
        
    # Finalize data structures required after the offline phase
    def _finalize_offline(self):
        self.EIM_approximation.init("online")
        
    def _print_greedy_interpolation_solve_message(self):
        print("solve interpolation for mu =", self.EIM_approximation.mu)
        
    # Update the snapshots container
    def add_to_snapshots(self, snapshot):
        self.snapshots_container.enrich(snapshot)
        
    # Update basis (greedy version)
    def update_basis_greedy(self, error, maximum_error):
        if abs(maximum_error) > 0.:
            self.EIM_approximation.basis_functions.enrich(error/maximum_error)
        else:
            # Trivial case, greedy will stop at the first iteration
            assert self.EIM_approximation.N == 0
            self.EIM_approximation.basis_functions.enrich(error) # error is actually zero
        self.EIM_approximation.basis_functions.save(self.EIM_approximation.folder["basis"], "basis")
        self.EIM_approximation.N += 1

    # Update basis (POD version)
    def compute_basis_POD(self):
        POD = self.EIM_approximation.parametrized_expression.create_POD_container()
        POD.store_snapshot(self.snapshots_container)
        (_, _, basis_functions, N) = POD.apply(self.Nmax, self.tol)
        self.EIM_approximation.basis_functions.enrich(basis_functions)
        self.EIM_approximation.basis_functions.save(self.EIM_approximation.folder["basis"], "basis")
        # do not increment self.EIM_approximation.N
        POD.print_eigenvalues(N)
        POD.save_eigenvalues_file(self.folder["post_processing"], "eigs")
        POD.save_retained_energy_file(self.folder["post_processing"], "retained_energy")
        return N
        
    def update_interpolation_locations(self, maximum_location):
        self.EIM_approximation.interpolation_locations.append(maximum_location)
        self.EIM_approximation.interpolation_locations.save(self.EIM_approximation.folder["reduced_operators"], "interpolation_locations")
    
    # Assemble the interpolation matrix
    def update_interpolation_matrix(self):
        self.EIM_approximation.interpolation_matrix[0] = evaluate(self.EIM_approximation.basis_functions[:self.EIM_approximation.N], self.EIM_approximation.interpolation_locations)
        self.EIM_approximation.interpolation_matrix.save(self.EIM_approximation.folder["reduced_operators"], "interpolation_matrix")
            
    # Load the precomputed snapshot
    def load_snapshot(self):
        assert self.EIM_approximation.basis_generation == "Greedy"
        mu = self.EIM_approximation.mu
        mu_index = self._training_set_parameters_to_snapshots_container_index[mu]
        assert mu == self.training_set[mu_index]
        return self.snapshots_container[mu_index]
        
    # Choose the next parameter in the offline stage in a greedy fashion
    def greedy(self):
        assert self.EIM_approximation.basis_generation == "Greedy"
        
        # Print some additional information on the consistency of the reduced basis
        self.EIM_approximation.solve()
        self.EIM_approximation.snapshot = self.load_snapshot()
        error = self.EIM_approximation.snapshot - self.EIM_approximation.basis_functions*self.EIM_approximation._interpolation_coefficients
        error_on_interpolation_locations = evaluate(error, self.EIM_approximation.interpolation_locations)
        (maximum_error, _) = max(abs(error))
        (maximum_error_on_interpolation_locations, _) = max(abs(error_on_interpolation_locations)) # for consistency check, should be zero
        print("interpolation error for current mu =", abs(maximum_error))
        print("interpolation error on interpolation locations for current mu =", abs(maximum_error_on_interpolation_locations))
        
        # Carry out the actual greedy search
        def solve_and_computer_error(mu):
            self.EIM_approximation.set_mu(mu)
            
            self.EIM_approximation.solve()
            self.EIM_approximation.snapshot = self.load_snapshot()
            (_, maximum_error, _) = self.EIM_approximation.compute_maximum_interpolation_error()
            return abs(maximum_error)
            
        print("find next mu")
        (error_max, error_argmax) = self.training_set.max(solve_and_computer_error)
        self.EIM_approximation.set_mu(self.training_set[error_argmax])
        self.greedy_selected_parameters.append(self.training_set[error_argmax])
        self.greedy_selected_parameters.save(self.folder["post_processing"], "mu_greedy")
        self.greedy_errors.append(error_max)
        self.greedy_errors.save(self.folder["post_processing"], "error_max")
        if abs(self.greedy_errors[0]) > 0.:
            return (abs(error_max), abs(error_max/self.greedy_errors[0]))
        else:
            # Trivial case, greedy will stop at the first iteration
            assert len(self.greedy_errors) == 1
            assert self.EIM_approximation.N == 1
            return (0., 0.)
    
    # Compute the error of the empirical interpolation approximation with respect to the
    # exact function over the testing set
    def error_analysis(self, N_generator=None, filename=None, **kwargs):
        assert len(kwargs) == 0 # not used in this method
            
        self._init_error_analysis(**kwargs)
        self._error_analysis(N_generator, filename, **kwargs)
        self._finalize_error_analysis(**kwargs)
        
    def _error_analysis(self, N_generator=None, filename=None, **kwargs):
        if N_generator is None:
            def N_generator(n):
                return n
                
        N = self.EIM_approximation.N
        interpolation_method_name = self.EIM_approximation.parametrized_expression.interpolation_method_name()
        description = self.EIM_approximation.parametrized_expression.description()
        
        print(TextBox(interpolation_method_name + " error analysis begins for" + "\n" + "\n".join(description), fill="="))
        print("")
        
        error_analysis_table = ErrorAnalysisTable(self.testing_set)
        error_analysis_table.set_Nmax(N)
        error_analysis_table.add_column("error", group_name="eim", operations=("mean", "max"))
        error_analysis_table.add_column("relative_error", group_name="eim", operations=("mean", "max"))
        
        for (mu_index, mu) in enumerate(self.testing_set):
            print(TextLine(interpolation_method_name + " " + str(mu_index), fill=":"))
            
            self.EIM_approximation.set_mu(mu)
            
            # Evaluate the exact function on the truth grid
            self.EIM_approximation.evaluate_parametrized_expression()
            
            for n in range(1, N + 1): # n = 1, ... N
                n_arg = N_generator(n)
                
                if n_arg is not None:
                    self.EIM_approximation.solve(n_arg)
                    (_, error, _) = self.EIM_approximation.compute_maximum_interpolation_error(n)
                    (_, relative_error, _) = self.EIM_approximation.compute_maximum_interpolation_relative_error(n)
                    error_analysis_table["error", n, mu_index] = abs(error)
                    error_analysis_table["relative_error", n, mu_index] = abs(relative_error)
                else:
                    error_analysis_table["error", n, mu_index] = NotImplemented
                    error_analysis_table["relative_error", n, mu_index] = NotImplemented
        
        # Print
        print("")
        print(error_analysis_table)
        
        print("")
        print(TextBox(interpolation_method_name + " error analysis ends for" + "\n" + "\n".join(description), fill="="))
        print("")
        
        # Export error analysis table
        error_analysis_table.save(self.folder["error_analysis"], "error_analysis" if filename is None else filename)
        
    # Compute the speedup of the empirical interpolation approximation with respect to the
    # exact function over the testing set
    def speedup_analysis(self, N_generator=None, filename=None, **kwargs):
        assert len(kwargs) == 0 # not used in this method
            
        self._init_speedup_analysis(**kwargs)
        self._speedup_analysis(N_generator, filename, **kwargs)
        self._finalize_speedup_analysis(**kwargs)
        
    # Initialize data structures required for the speedup analysis phase
    def _init_speedup_analysis(self, **kwargs):
        # Make sure to clean up snapshot cache to ensure that parametrized
        # expression evaluation is actually carried out
        self.EIM_approximation.snapshot_cache.clear()
        # ... and also disable the capability of importing/exporting truth solutions
        self.disable_import_solution = PatchInstanceMethod(self.EIM_approximation, "import_solution", lambda self_, folder, filename, solution=None: False)
        self.disable_export_solution = PatchInstanceMethod(self.EIM_approximation, "export_solution", lambda self_, folder, filename, solution=None: None)
        self.disable_import_solution.patch()
        self.disable_export_solution.patch()
        
    def _speedup_analysis(self, N_generator=None, filename=None, **kwargs):
        if N_generator is None:
            def N_generator(n):
                return n
                
        N = self.EIM_approximation.N
        interpolation_method_name = self.EIM_approximation.parametrized_expression.interpolation_method_name()
        description = self.EIM_approximation.parametrized_expression.description()
        
        print(TextBox(interpolation_method_name + " speedup analysis begins for" + "\n" + "\n".join(description), fill="="))
        print("")
        
        speedup_analysis_table = SpeedupAnalysisTable(self.testing_set)
        speedup_analysis_table.set_Nmax(N)
        speedup_analysis_table.add_column("speedup", group_name="speedup", operations=("min", "mean", "max"))
        
        evaluate_timer = Timer("parallel")
        EIM_timer = Timer("serial")
        
        for (mu_index, mu) in enumerate(self.testing_set):
            print(TextLine(interpolation_method_name + " " + str(mu_index), fill=":"))
            
            self.EIM_approximation.set_mu(mu)
            
            # Evaluate the exact function on the truth grid
            evaluate_timer.start()
            self.EIM_approximation.evaluate_parametrized_expression()
            elapsed_evaluate = evaluate_timer.stop()
            
            for n in range(1, N + 1): # n = 1, ... N
                n_arg = N_generator(n)
                
                if n_arg is not None:
                    EIM_timer.start()
                    self.EIM_approximation.solve(n_arg)
                    elapsed_EIM = EIM_timer.stop()
                    speedup_analysis_table["speedup", n, mu_index] = elapsed_evaluate/elapsed_EIM
                else:
                    speedup_analysis_table["speedup", n, mu_index] = NotImplemented
        
        # Print
        print("")
        print(speedup_analysis_table)
        
        print("")
        print(TextBox(interpolation_method_name + " speedup analysis ends for" + "\n" + "\n".join(description), fill="="))
        print("")
        
        # Export speedup analysis table
        speedup_analysis_table.save(self.folder["speedup_analysis"], "speedup_analysis" if filename is None else filename)
        
    # Finalize data structures required after the speedup analysis phase
    def _finalize_speedup_analysis(self, **kwargs):
        # Restore the capability to import/export truth solutions
        self.disable_import_solution.unpatch()
        self.disable_export_solution.unpatch()
        del self.disable_import_solution
        del self.disable_export_solution
class SCMApproximationReductionMethod(ReductionMethod):

    # Default initialization of members
    def __init__(self, SCM_approximation, folder_prefix):
        # Call the parent initialization
        ReductionMethod.__init__(self, folder_prefix)

        # $$ OFFLINE DATA STRUCTURES $$ #
        # High fidelity problem
        self.SCM_approximation = SCM_approximation
        # I/O
        self.folder["post_processing"] = os.path.join(self.folder_prefix,
                                                      "post_processing")
        self.greedy_selected_parameters = SCM_approximation.greedy_selected_parameters
        self.greedy_error_estimators = GreedyErrorEstimatorsList()

    # OFFLINE: set the elements in the training set.
    def initialize_training_set(self,
                                ntrain,
                                enable_import=True,
                                sampling=None,
                                **kwargs):
        assert enable_import
        import_successful = ReductionMethod.initialize_training_set(
            self, self.SCM_approximation.mu_range, ntrain, enable_import,
            sampling, **kwargs)
        self.SCM_approximation.training_set = self.training_set
        return import_successful

    def initialize_testing_set(self,
                               ntest,
                               enable_import=False,
                               sampling=None,
                               **kwargs):
        return ReductionMethod.initialize_testing_set(
            self, self.SCM_approximation.mu_range, ntest, enable_import,
            sampling, **kwargs)

    # Perform the offline phase of SCM
    def offline(self):
        need_to_do_offline_stage = self._init_offline()
        if need_to_do_offline_stage:
            self._offline()
        self._finalize_offline()
        return self.SCM_approximation

    # Initialize data structures required for the offline phase
    def _init_offline(self):
        # Prepare folders and init SCM approximation
        required_folders = Folders()
        required_folders.update(self.folder)
        required_folders.update(self.SCM_approximation.folder)
        optional_folders = Folders()
        optional_folders["cache"] = required_folders.pop("cache")
        # cache does not affect the availability of offline data
        optional_folders["testing_set"] = required_folders.pop("testing_set")
        # testing set is required only in the error/speedup analysis
        optional_folders["error_analysis"] = required_folders.pop(
            "error_analysis")
        # error analysis folder is required only in the error analysis
        optional_folders["speedup_analysis"] = required_folders.pop(
            "speedup_analysis")
        # speedup analysis folder is required only in the speedup analysis
        at_least_one_required_folder_created = required_folders.create()
        at_least_one_optional_folder_created = optional_folders.create(
        )  # noqa: F841
        if not at_least_one_required_folder_created:
            return False  # offline construction should be skipped, since data are already available
        else:
            self.SCM_approximation.init("offline")
            return True  # offline construction should be carried out

    def _offline(self):
        print(TextBox("SCM offline phase begins", fill="="))
        print("")

        # Compute the bounding box \mathcal{B}
        self.compute_bounding_box()
        print("")

        # Arbitrarily start from the first parameter in the training set
        self.SCM_approximation.set_mu(self.training_set[0])
        relative_error_estimator_max = 2. * self.tol

        while self.SCM_approximation.N < self.Nmax and relative_error_estimator_max >= self.tol:
            print(
                TextLine("SCM N = " + str(self.SCM_approximation.N), fill="~"))

            # Store the greedy parameter
            self.store_greedy_selected_parameters()

            # Evaluate the stability factor
            print("evaluate the stability factor for mu =",
                  self.SCM_approximation.mu)
            (stability_factor,
             eigenvector) = self.SCM_approximation.evaluate_stability_factor()
            print("stability factor =", stability_factor)

            # Update data structures related to upper bound vectors
            upper_bound_vector = self.compute_upper_bound_vector(eigenvector)
            self.update_upper_bound_vectors(upper_bound_vector)

            # Prepare for next iteration
            print("find next mu")
            (error_estimator_max, relative_error_estimator_max) = self.greedy()
            print("maximum SCM error estimator =", error_estimator_max)
            print("maximum SCM relative error estimator =",
                  relative_error_estimator_max)

            print("")

        print(TextBox("SCM offline phase ends", fill="="))
        print("")

    # Finalize data structures required after the offline phase
    def _finalize_offline(self):
        self.SCM_approximation.init("online")

    # Compute the bounding box \mathcal{B}
    def compute_bounding_box(self):
        # Resize the bounding box storage
        Q = self.SCM_approximation.truth_problem.Q[
            "stability_factor_left_hand_matrix"]

        for q in range(Q):
            # Compute the minimum eigenvalue
            minimum_eigenvalue_calculator = ParametrizedStabilityFactorEigenProblem(
                self.SCM_approximation.truth_problem,
                "smallest",
                self.SCM_approximation.truth_problem.
                _eigen_solver_parameters["bounding_box_minimum"],
                self.folder_prefix,
                expansion_index=q)
            minimum_eigenvalue_calculator.init()
            (self.SCM_approximation.bounding_box_min[q],
             _) = minimum_eigenvalue_calculator.solve()
            print("bounding_box_min[" + str(q) + "] = " +
                  str(self.SCM_approximation.bounding_box_min[q]))

            # Compute the maximum eigenvalue
            maximum_eigenvalue_calculator = ParametrizedStabilityFactorEigenProblem(
                self.SCM_approximation.truth_problem,
                "largest",
                self.SCM_approximation.truth_problem.
                _eigen_solver_parameters["bounding_box_maximum"],
                self.folder_prefix,
                expansion_index=q)
            maximum_eigenvalue_calculator.init()
            (self.SCM_approximation.bounding_box_max[q],
             _) = maximum_eigenvalue_calculator.solve()
            print("bounding_box_max[" + str(q) + "] = " +
                  str(self.SCM_approximation.bounding_box_max[q]))

        # Save to file
        self.SCM_approximation.bounding_box_min.save(
            self.SCM_approximation.folder["reduced_operators"],
            "bounding_box_min")
        self.SCM_approximation.bounding_box_max.save(
            self.SCM_approximation.folder["reduced_operators"],
            "bounding_box_max")

    # Store the greedy parameter
    def store_greedy_selected_parameters(self):
        mu = self.SCM_approximation.mu

        self.SCM_approximation.greedy_selected_parameters.append(mu)
        self.SCM_approximation.N = len(
            self.SCM_approximation.greedy_selected_parameters)

        # Save to file
        self.SCM_approximation.greedy_selected_parameters.save(
            self.SCM_approximation.folder["reduced_operators"],
            "greedy_selected_parameters")

    def compute_upper_bound_vector(self, u):
        Q = self.SCM_approximation.truth_problem.Q[
            "stability_factor_left_hand_matrix"]
        A = self.SCM_approximation.truth_problem.operator[
            "stability_factor_left_hand_matrix"]
        B = self.SCM_approximation.truth_problem.operator[
            "stability_factor_right_hand_matrix"]
        assert len(B) == 1
        normalization = transpose(u) * B[0] * u
        upper_bound_vector = OnlineVector(Q)
        for q in range(Q):
            upper_bound_vector[q] = (transpose(u) * A[q] * u) / normalization
        return upper_bound_vector

    def update_upper_bound_vectors(self, upper_bound_vector):
        self.SCM_approximation.upper_bound_vectors.append(upper_bound_vector)
        self.SCM_approximation.upper_bound_vectors.save(
            self.SCM_approximation.folder["reduced_operators"],
            "upper_bound_vectors")

    # Choose the next parameter in the offline stage in a greedy fashion
    def greedy(self):
        def solve_and_estimate_error(mu):
            self.SCM_approximation.set_mu(mu)

            stability_factor_lower_bound = self.SCM_approximation.get_stability_factor_lower_bound(
            )
            stability_factor_upper_bound = self.SCM_approximation.get_stability_factor_upper_bound(
            )
            ratio = stability_factor_lower_bound / stability_factor_upper_bound

            if ratio < 0. and not isclose(ratio, 0.):  # if ratio << 0
                print("SCM warning at mu = " + str(mu) +
                      ": stability factor lower bound = " +
                      str(stability_factor_lower_bound) + " < 0")
            if ratio > 1. and not isclose(ratio, 1.):  # if ratio >> 1
                print("SCM warning at mu = " + str(mu) +
                      ": stability factor lower bound = " +
                      str(stability_factor_lower_bound) +
                      " > stability factor upper bound = " +
                      str(stability_factor_upper_bound))

            error_estimator = 1. - ratio
            return error_estimator

        (error_estimator_max, error_estimator_argmax
         ) = self.training_set.max(solve_and_estimate_error)
        self.SCM_approximation.set_mu(
            self.training_set[error_estimator_argmax])
        self.greedy_error_estimators.append(error_estimator_max)
        self.greedy_error_estimators.save(self.folder["post_processing"],
                                          "error_estimator_max")
        return (error_estimator_max,
                error_estimator_max / self.greedy_error_estimators[0])

    # Initialize data structures required for the error analysis phase
    def _init_error_analysis(self, **kwargs):
        # Initialize reduced order data structures in the SCM online problem
        self.SCM_approximation.init("online")

    # Compute the error of the scm approximation with respect to the
    # exact stability factor over the testing set
    def error_analysis(self, N_generator=None, filename=None, **kwargs):
        assert len(kwargs) == 0  # not used in this method

        self._init_error_analysis(**kwargs)
        self._error_analysis(N_generator, filename, **kwargs)
        self._finalize_error_analysis(**kwargs)

    def _error_analysis(self, N_generator=None, filename=None, **kwargs):
        if N_generator is None:

            def N_generator():
                N = self.SCM_approximation.N
                for n in range(1, N + 1):  # n = 1, ... N
                    yield n

        def N_generator_max():
            *_, Nmax = N_generator()
            return Nmax

        print(TextBox("SCM error analysis begins", fill="="))
        print("")

        error_analysis_table = ErrorAnalysisTable(self.testing_set)
        error_analysis_table.set_Nmax(N_generator_max())
        error_analysis_table.add_column("normalized_error",
                                        group_name="scm",
                                        operations=("min", "mean", "max"))

        for (mu_index, mu) in enumerate(self.testing_set):
            print(TextLine("SCM " + str(mu_index), fill="~"))

            self.SCM_approximation.set_mu(mu)

            (exact_stability_factor,
             _) = self.SCM_approximation.evaluate_stability_factor()
            for n in N_generator():
                stability_factor_lower_bound = self.SCM_approximation.get_stability_factor_lower_bound(
                    n)
                stability_factor_upper_bound = self.SCM_approximation.get_stability_factor_upper_bound(
                    n)
                ratio_lower_bound_to_upper_bound = stability_factor_lower_bound / stability_factor_upper_bound
                ratio_lower_bound_to_exact = stability_factor_lower_bound / exact_stability_factor

                if ratio_lower_bound_to_upper_bound < 0. and not isclose(
                        ratio_lower_bound_to_upper_bound, 0.):
                    # if ratio_lower_bound_to_upper_bound << 0
                    print("SCM warning at mu = " + str(mu) +
                          ": stability factor lower bound = " +
                          str(stability_factor_lower_bound) + " < 0")
                if ratio_lower_bound_to_upper_bound > 1. and not isclose(
                        ratio_lower_bound_to_upper_bound, 1.):
                    # if ratio_lower_bound_to_upper_bound >> 1
                    print("SCM warning at mu = " + str(mu) +
                          ": stability factor lower bound = " +
                          str(stability_factor_lower_bound) +
                          " > stability factor upper bound = " +
                          str(stability_factor_upper_bound))
                if ratio_lower_bound_to_exact > 1. and not isclose(
                        ratio_lower_bound_to_exact, 1.):
                    # if ratio_lower_bound_to_exact >> 1
                    print("SCM warning at mu = " + str(mu) +
                          ": stability factor lower bound = " +
                          str(stability_factor_lower_bound) +
                          " > exact stability factor =" +
                          str(exact_stability_factor))

                error_analysis_table["normalized_error", n, mu_index] = (
                    exact_stability_factor - stability_factor_lower_bound
                ) / stability_factor_upper_bound

        # Print
        print("")
        print(error_analysis_table)

        print("")
        print(TextBox("SCM error analysis ends", fill="="))
        print("")

        # Export error analysis table
        error_analysis_table.save(
            self.folder["error_analysis"],
            "error_analysis" if filename is None else filename)

    # Compute the speedup of the scm approximation with respect to the
    # exact stability factor over the testing set
    def speedup_analysis(self, N_generator=None, filename=None, **kwargs):
        assert len(kwargs) == 0  # not used in this method

        self._init_speedup_analysis(**kwargs)
        self._speedup_analysis(N_generator, filename, **kwargs)
        self._finalize_speedup_analysis(**kwargs)

    # Initialize data structures required for the speedup analysis phase
    def _init_speedup_analysis(self, **kwargs):
        # Make sure to clean up snapshot cache to ensure that parametrized
        # expression evaluation is actually carried out
        self.SCM_approximation._stability_factor_lower_bound_cache.clear()
        self.SCM_approximation._stability_factor_upper_bound_cache.clear()
        self.SCM_approximation.stability_factor_calculator._eigenvalue_cache.clear(
        )
        self.SCM_approximation.stability_factor_calculator._eigenvector_cache.clear(
        )

    def _speedup_analysis(self, N_generator=None, filename=None, **kwargs):
        if N_generator is None:

            def N_generator():
                N = self.SCM_approximation.N
                for n in range(1, N + 1):  # n = 1, ... N
                    yield n

        def N_generator_max():
            *_, Nmax = N_generator()
            return Nmax

        print(TextBox("SCM speedup analysis begins", fill="="))
        print("")

        speedup_analysis_table = SpeedupAnalysisTable(self.testing_set)
        speedup_analysis_table.set_Nmax(N_generator_max())
        speedup_analysis_table.add_column("speedup",
                                          group_name="speedup",
                                          operations=("min", "mean", "max"))

        exact_timer = Timer("parallel")
        SCM_timer = Timer("serial")

        for (mu_index, mu) in enumerate(self.testing_set):
            print(TextLine("SCM " + str(mu_index), fill="~"))

            self.SCM_approximation.set_mu(mu)

            exact_timer.start()
            self.SCM_approximation.evaluate_stability_factor()
            elapsed_exact = exact_timer.stop()

            for n in N_generator():
                SCM_timer.start()
                self.SCM_approximation.get_stability_factor_lower_bound(n)
                self.SCM_approximation.get_stability_factor_upper_bound(n)
                elapsed_SCM = SCM_timer.stop()
                speedup_analysis_table["speedup", n,
                                       mu_index] = elapsed_exact / elapsed_SCM

        # Print
        print("")
        print(speedup_analysis_table)

        print("")
        print(TextBox("SCM speedup analysis ends", fill="="))
        print("")

        # Export speedup analysis table
        speedup_analysis_table.save(
            self.folder["speedup_analysis"],
            "speedup_analysis" if filename is None else filename)
Beispiel #7
0
    class RBReduction_Class(DifferentialProblemReductionMethod_DerivedClass):
        """
        The folders used to store the snapshots and for the post processing data, the parameters for the greedy algorithm and the error estimator evaluations are initialized.
        
        :param truth_problem: class of the truth problem to be solved.
        :return: reduced RB class.
       
        """
        def __init__(self, truth_problem, **kwargs):
            # Call the parent initialization
            DifferentialProblemReductionMethod_DerivedClass.__init__(
                self, truth_problem, **kwargs)

            # Declare a GS object
            self.GS = None  # GramSchmidt (for problems with one component) or dict of GramSchmidt (for problem with several components)
            # I/O
            self.folder["snapshots"] = os.path.join(self.folder_prefix,
                                                    "snapshots")
            self.folder["post_processing"] = os.path.join(
                self.folder_prefix, "post_processing")
            self.greedy_selected_parameters = GreedySelectedParametersList()
            self.greedy_error_estimators = GreedyErrorEstimatorsList()
            self.label = "RB"

        def _init_offline(self):
            # Call parent to initialize inner product and reduced problem
            output = DifferentialProblemReductionMethod_DerivedClass._init_offline(
                self)

            # Declare a new GS for each basis component
            if len(self.truth_problem.components) > 1:
                self.GS = dict()
                for component in self.truth_problem.components:
                    assert len(
                        self.truth_problem.inner_product[component]) == 1
                    inner_product = self.truth_problem.inner_product[
                        component][0]
                    self.GS[component] = GramSchmidt(self.truth_problem.V,
                                                     inner_product)
            else:
                assert len(self.truth_problem.inner_product) == 1
                inner_product = self.truth_problem.inner_product[0]
                self.GS = GramSchmidt(self.truth_problem.V, inner_product)

            # Return
            return output

        def offline(self):
            """
            It performs the offline phase of the reduced order model.
            
            :return: reduced_problem where all offline data are stored.
            """
            need_to_do_offline_stage = self._init_offline()
            if need_to_do_offline_stage:
                self._offline()
            self._finalize_offline()
            return self.reduced_problem

        @snapshot_links_to_cache
        def _offline(self):
            print(
                TextBox(self.truth_problem.name() + " " + self.label +
                        " offline phase begins",
                        fill="="))
            print("")

            # Initialize first parameter to be used
            self.reduced_problem.build_reduced_operators()
            self.reduced_problem.build_error_estimation_operators()
            (absolute_error_estimator_max,
             relative_error_estimator_max) = self.greedy()
            print(
                "initial maximum absolute error estimator over training set =",
                absolute_error_estimator_max)
            print(
                "initial maximum relative error estimator over training set =",
                relative_error_estimator_max)

            print("")

            iteration = 0
            while self.reduced_problem.N < self.Nmax and relative_error_estimator_max >= self.tol:
                print(TextLine("N = " + str(self.reduced_problem.N), fill="#"))

                print("truth solve for mu =", self.truth_problem.mu)
                snapshot = self.truth_problem.solve()
                self.truth_problem.export_solution(self.folder["snapshots"],
                                                   "truth_" + str(iteration),
                                                   snapshot)
                snapshot = self.postprocess_snapshot(snapshot, iteration)

                print("update basis matrix")
                self.update_basis_matrix(snapshot)
                iteration += 1

                print("build reduced operators")
                self.reduced_problem.build_reduced_operators()

                print("reduced order solve")
                self.reduced_problem.solve()

                print("build operators for error estimation")
                self.reduced_problem.build_error_estimation_operators()

                (absolute_error_estimator_max,
                 relative_error_estimator_max) = self.greedy()
                print("maximum absolute error estimator over training set =",
                      absolute_error_estimator_max)
                print("maximum relative error estimator over training set =",
                      relative_error_estimator_max)

                print("")

            print(
                TextBox(self.truth_problem.name() + " " + self.label +
                        " offline phase ends",
                        fill="="))
            print("")

        def update_basis_matrix(self, snapshot):
            """
            It updates basis matrix.
            
            :param snapshot: last offline solution calculated.
            """
            if len(self.truth_problem.components) > 1:
                for component in self.truth_problem.components:
                    new_basis_function = self.GS[component].apply(
                        snapshot,
                        self.reduced_problem.basis_functions[component]
                        [self.reduced_problem.N_bc[component]:],
                        component=component)
                    self.reduced_problem.basis_functions.enrich(
                        new_basis_function, component=component)
                    self.reduced_problem.N[component] += 1
                self.reduced_problem.basis_functions.save(
                    self.reduced_problem.folder["basis"], "basis")
            else:
                new_basis_function = self.GS.apply(
                    snapshot, self.reduced_problem.
                    basis_functions[self.reduced_problem.N_bc:])
                self.reduced_problem.basis_functions.enrich(new_basis_function)
                self.reduced_problem.N += 1
                self.reduced_problem.basis_functions.save(
                    self.reduced_problem.folder["basis"], "basis")

        def greedy(self):
            """
            It chooses the next parameter in the offline stage in a greedy fashion: wrapper with post processing of the result (in particular, set greedily selected parameter and save to file)
            
            :return: max error estimator and the comparison with the first one calculated.
            """
            (error_estimator_max, error_estimator_argmax) = self._greedy()
            self.truth_problem.set_mu(
                self.training_set[error_estimator_argmax])
            self.greedy_selected_parameters.append(
                self.training_set[error_estimator_argmax])
            self.greedy_selected_parameters.save(
                self.folder["post_processing"], "mu_greedy")
            self.greedy_error_estimators.append(error_estimator_max)
            self.greedy_error_estimators.save(self.folder["post_processing"],
                                              "error_estimator_max")
            return (error_estimator_max,
                    error_estimator_max / self.greedy_error_estimators[0])

        def _greedy(self):
            """
            It chooses the next parameter in the offline stage in a greedy fashion. Internal method.
            
            :return: max error estimator and the respective parameter.
            """

            if self.reduced_problem.N > 0:  # skip during initialization
                # Print some additional information on the consistency of the reduced basis
                print("absolute error for current mu =",
                      self.reduced_problem.compute_error())
                print("absolute error estimator for current mu =",
                      self.reduced_problem.estimate_error())

            # Carry out the actual greedy search
            def solve_and_estimate_error(mu):
                self.reduced_problem.set_mu(mu)
                self.reduced_problem.solve()
                error_estimator = self.reduced_problem.estimate_error()
                logger.log(
                    DEBUG, "Error estimator for mu = " + str(mu) + " is " +
                    str(error_estimator))
                return error_estimator

            if self.reduced_problem.N == 0:
                print("find initial mu")
            else:
                print("find next mu")

            return self.training_set.max(solve_and_estimate_error)

        def error_analysis(self, N_generator=None, filename=None, **kwargs):
            """
            It computes the error of the reduced order approximation with respect to the full order one over the testing set.
            
            :param N_generator: generator of dimension of reduced problem.
            """
            self._init_error_analysis(**kwargs)
            self._error_analysis(N_generator, filename, **kwargs)
            self._finalize_error_analysis(**kwargs)

        def _error_analysis(self, N_generator=None, filename=None, **kwargs):
            if N_generator is None:

                def N_generator():
                    N = self.reduced_problem.N
                    if isinstance(N, dict):
                        N = min(N.values())
                    for n in range(1, N + 1):  # n = 1, ... N
                        yield n

            if "components" in kwargs:
                components = kwargs["components"]
            else:
                components = self.truth_problem.components

            def N_generator_items():
                for n in N_generator():
                    assert isinstance(n, (dict, int))
                    if isinstance(n, int):
                        yield (n, n)
                    elif isinstance(n, dict):
                        assert len(n) == 1
                        (n_int, n_online_size_dict) = n.popitem()
                        assert isinstance(n_int, int)
                        assert isinstance(n_online_size_dict, OnlineSizeDict)
                        yield (n_int, n_online_size_dict)
                    else:
                        raise TypeError(
                            "Invalid item generated by N_generator")

            def N_generator_max():
                *_, Nmax = N_generator_items()
                assert isinstance(Nmax, tuple)
                assert len(Nmax) == 2
                assert isinstance(Nmax[0], int)
                return Nmax[0]

            print(
                TextBox(self.truth_problem.name() + " " + self.label +
                        " error analysis begins",
                        fill="="))
            print("")

            error_analysis_table = ErrorAnalysisTable(self.testing_set)
            error_analysis_table.set_Nmax(N_generator_max())
            if len(components) > 1:
                all_components_string = "".join(components)
                for component in components:
                    error_analysis_table.add_column("error_" + component,
                                                    group_name="solution_" +
                                                    component + "_error",
                                                    operations=("mean", "max"))
                    error_analysis_table.add_column(
                        "relative_error_" + component,
                        group_name="solution_" + component + "_relative_error",
                        operations=("mean", "max"))
                error_analysis_table.add_column(
                    "error_" + all_components_string,
                    group_name="solution_" + all_components_string + "_error",
                    operations=("mean", "max"))
                error_analysis_table.add_column(
                    "error_estimator_" + all_components_string,
                    group_name="solution_" + all_components_string + "_error",
                    operations=("mean", "max"))
                error_analysis_table.add_column(
                    "effectivity_" + all_components_string,
                    group_name="solution_" + all_components_string + "_error",
                    operations=("min", "mean", "max"))
                error_analysis_table.add_column(
                    "relative_error_" + all_components_string,
                    group_name="solution_" + all_components_string +
                    "_relative_error",
                    operations=("mean", "max"))
                error_analysis_table.add_column(
                    "relative_error_estimator_" + all_components_string,
                    group_name="solution_" + all_components_string +
                    "_relative_error",
                    operations=("mean", "max"))
                error_analysis_table.add_column(
                    "relative_effectivity_" + all_components_string,
                    group_name="solution_" + all_components_string +
                    "_relative_error",
                    operations=("min", "mean", "max"))
            else:
                component = components[0]
                error_analysis_table.add_column("error_" + component,
                                                group_name="solution_" +
                                                component + "_error",
                                                operations=("mean", "max"))
                error_analysis_table.add_column("error_estimator_" + component,
                                                group_name="solution_" +
                                                component + "_error",
                                                operations=("mean", "max"))
                error_analysis_table.add_column(
                    "effectivity_" + component,
                    group_name="solution_" + component + "_error",
                    operations=("min", "mean", "max"))
                error_analysis_table.add_column("relative_error_" + component,
                                                group_name="solution_" +
                                                component + "_relative_error",
                                                operations=("mean", "max"))
                error_analysis_table.add_column(
                    "relative_error_estimator_" + component,
                    group_name="solution_" + component + "_relative_error",
                    operations=("mean", "max"))
                error_analysis_table.add_column(
                    "relative_effectivity_" + component,
                    group_name="solution_" + component + "_relative_error",
                    operations=("min", "mean", "max"))
            error_analysis_table.add_column("error_output",
                                            group_name="output_error",
                                            operations=("mean", "max"))
            error_analysis_table.add_column("error_estimator_output",
                                            group_name="output_error",
                                            operations=("mean", "max"))
            error_analysis_table.add_column("effectivity_output",
                                            group_name="output_error",
                                            operations=("min", "mean", "max"))
            error_analysis_table.add_column("relative_error_output",
                                            group_name="output_relative_error",
                                            operations=("mean", "max"))
            error_analysis_table.add_column("relative_error_estimator_output",
                                            group_name="output_relative_error",
                                            operations=("mean", "max"))
            error_analysis_table.add_column("relative_effectivity_output",
                                            group_name="output_relative_error",
                                            operations=("min", "mean", "max"))

            for (mu_index, mu) in enumerate(self.testing_set):
                print(TextLine(str(mu_index), fill="#"))

                self.reduced_problem.set_mu(mu)

                for (n_int, n_arg) in N_generator_items():
                    self.reduced_problem.solve(n_arg, **kwargs)
                    error = self.reduced_problem.compute_error(**kwargs)
                    if len(components) > 1:
                        error[all_components_string] = sqrt(
                            sum([
                                error[component]**2 for component in components
                            ]))
                    error_estimator = self.reduced_problem.estimate_error()
                    relative_error = self.reduced_problem.compute_relative_error(
                        **kwargs)
                    if len(components) > 1:
                        relative_error[all_components_string] = sqrt(
                            sum([
                                relative_error[component]**2
                                for component in components
                            ]))
                    relative_error_estimator = self.reduced_problem.estimate_relative_error(
                    )

                    self.reduced_problem.compute_output()
                    error_output = self.reduced_problem.compute_error_output(
                        **kwargs)
                    error_output_estimator = self.reduced_problem.estimate_error_output(
                    )
                    relative_error_output = self.reduced_problem.compute_relative_error_output(
                        **kwargs)
                    relative_error_output_estimator = self.reduced_problem.estimate_relative_error_output(
                    )

                    if len(components) > 1:
                        for component in components:
                            error_analysis_table["error_" + component, n_int,
                                                 mu_index] = error[component]
                            error_analysis_table[
                                "relative_error_" + component, n_int,
                                mu_index] = relative_error[component]
                        error_analysis_table[
                            "error_" + all_components_string, n_int,
                            mu_index] = error[all_components_string]
                        error_analysis_table["error_estimator_" +
                                             all_components_string, n_int,
                                             mu_index] = error_estimator
                        error_analysis_table[
                            "effectivity_" + all_components_string, n_int,
                            mu_index] = error_analysis_table[
                                "error_estimator_" + all_components_string,
                                n_int, mu_index] / error_analysis_table[
                                    "error_" + all_components_string, n_int,
                                    mu_index]
                        error_analysis_table[
                            "relative_error_" + all_components_string, n_int,
                            mu_index] = relative_error[all_components_string]
                        error_analysis_table[
                            "relative_error_estimator_" +
                            all_components_string, n_int,
                            mu_index] = relative_error_estimator
                        error_analysis_table[
                            "relative_effectivity_" + all_components_string,
                            n_int, mu_index] = error_analysis_table[
                                "relative_error_estimator_" +
                                all_components_string, n_int,
                                mu_index] / error_analysis_table[
                                    "relative_error_" + all_components_string,
                                    n_int, mu_index]
                    else:
                        component = components[0]
                        error_analysis_table["error_" + component, n_int,
                                             mu_index] = error
                        error_analysis_table["error_estimator_" + component,
                                             n_int, mu_index] = error_estimator
                        error_analysis_table[
                            "effectivity_" + component, n_int,
                            mu_index] = error_analysis_table[
                                "error_estimator_" + component, n_int,
                                mu_index] / error_analysis_table[
                                    "error_" + component, n_int, mu_index]
                        error_analysis_table["relative_error_" + component,
                                             n_int, mu_index] = relative_error
                        error_analysis_table[
                            "relative_error_estimator_" + component, n_int,
                            mu_index] = relative_error_estimator
                        error_analysis_table[
                            "relative_effectivity_" + component, n_int,
                            mu_index] = error_analysis_table[
                                "relative_error_estimator_" + component, n_int,
                                mu_index] / error_analysis_table[
                                    "relative_error_" + component, n_int,
                                    mu_index]

                    error_analysis_table["error_output", n_int,
                                         mu_index] = error_output
                    error_analysis_table["error_estimator_output", n_int,
                                         mu_index] = error_output_estimator
                    error_analysis_table[
                        "effectivity_output", n_int,
                        mu_index] = error_analysis_table[
                            "error_estimator_output", n_int,
                            mu_index] / error_analysis_table["error_output",
                                                             n_int, mu_index]
                    error_analysis_table["relative_error_output", n_int,
                                         mu_index] = relative_error_output
                    error_analysis_table[
                        "relative_error_estimator_output", n_int,
                        mu_index] = relative_error_output_estimator
                    error_analysis_table[
                        "relative_effectivity_output", n_int,
                        mu_index] = error_analysis_table[
                            "relative_error_estimator_output", n_int,
                            mu_index] / error_analysis_table[
                                "relative_error_output", n_int, mu_index]

            # Print
            print("")
            print(error_analysis_table)

            print("")
            print(
                TextBox(self.truth_problem.name() + " " + self.label +
                        " error analysis ends",
                        fill="="))
            print("")

            # Export error analysis table
            error_analysis_table.save(
                self.folder["error_analysis"],
                "error_analysis" if filename is None else filename)

        def speedup_analysis(self, N_generator=None, filename=None, **kwargs):
            """
            It computes the speedup of the reduced order approximation with respect to the full order one over the testing set.
            
            :param N_generator: generator of dimension of the reduced problem.
            """
            self._init_speedup_analysis(**kwargs)
            self._speedup_analysis(N_generator, filename, **kwargs)
            self._finalize_speedup_analysis(**kwargs)

        def _speedup_analysis(self, N_generator=None, filename=None, **kwargs):
            if N_generator is None:

                def N_generator():
                    N = self.reduced_problem.N
                    if isinstance(N, dict):
                        N = min(N.values())
                    for n in range(1, N + 1):  # n = 1, ... N
                        yield n

            def N_generator_items():
                for n in N_generator():
                    assert isinstance(n, (dict, int))
                    if isinstance(n, int):
                        yield (n, n)
                    elif isinstance(n, dict):
                        assert len(n) == 1
                        (n_int, n_online_size_dict) = n.popitem()
                        assert isinstance(n_int, int)
                        assert isinstance(n_online_size_dict, OnlineSizeDict)
                        yield (n_int, n_online_size_dict)
                    else:
                        raise TypeError(
                            "Invalid item generated by N_generator")

            def N_generator_max():
                *_, Nmax = N_generator_items()
                assert isinstance(Nmax, tuple)
                assert len(Nmax) == 2
                assert isinstance(Nmax[0], int)
                return Nmax[0]

            print(
                TextBox(self.truth_problem.name() + " " + self.label +
                        " speedup analysis begins",
                        fill="="))
            print("")

            speedup_analysis_table = SpeedupAnalysisTable(self.testing_set)
            speedup_analysis_table.set_Nmax(N_generator_max())
            speedup_analysis_table.add_column("speedup_solve",
                                              group_name="speedup_solve",
                                              operations=("min", "mean",
                                                          "max"))
            speedup_analysis_table.add_column(
                "speedup_solve_and_estimate_error",
                group_name="speedup_solve_and_estimate_error",
                operations=("min", "mean", "max"))
            speedup_analysis_table.add_column(
                "speedup_solve_and_estimate_relative_error",
                group_name="speedup_solve_and_estimate_relative_error",
                operations=("min", "mean", "max"))
            speedup_analysis_table.add_column("speedup_output",
                                              group_name="speedup_output",
                                              operations=("min", "mean",
                                                          "max"))
            speedup_analysis_table.add_column(
                "speedup_output_and_estimate_error_output",
                group_name="speedup_output_and_estimate_error_output",
                operations=("min", "mean", "max"))
            speedup_analysis_table.add_column(
                "speedup_output_and_estimate_relative_error_output",
                group_name="speedup_output_and_estimate_relative_error_output",
                operations=("min", "mean", "max"))

            truth_timer = Timer("parallel")
            reduced_timer = Timer("serial")

            for (mu_index, mu) in enumerate(self.testing_set):
                print(TextLine(str(mu_index), fill="#"))

                self.reduced_problem.set_mu(mu)

                truth_timer.start()
                self.truth_problem.solve(**kwargs)
                elapsed_truth_solve = truth_timer.stop()

                truth_timer.start()
                self.truth_problem.compute_output()
                elapsed_truth_output = truth_timer.stop()

                for (n_int, n_arg) in N_generator_items():
                    reduced_timer.start()
                    solution = self.reduced_problem.solve(n_arg, **kwargs)
                    elapsed_reduced_solve = reduced_timer.stop()

                    truth_timer.start()
                    self.reduced_problem.compute_error(**kwargs)
                    elapsed_error = truth_timer.stop()

                    reduced_timer.start()
                    error_estimator = self.reduced_problem.estimate_error()
                    elapsed_error_estimator = reduced_timer.stop()

                    truth_timer.start()
                    self.reduced_problem.compute_relative_error(**kwargs)
                    elapsed_relative_error = truth_timer.stop()

                    reduced_timer.start()
                    relative_error_estimator = self.reduced_problem.estimate_relative_error(
                    )
                    elapsed_relative_error_estimator = reduced_timer.stop()

                    reduced_timer.start()
                    output = self.reduced_problem.compute_output()
                    elapsed_reduced_output = reduced_timer.stop()

                    truth_timer.start()
                    self.reduced_problem.compute_error_output(**kwargs)
                    elapsed_error_output = truth_timer.stop()

                    reduced_timer.start()
                    error_estimator_output = self.reduced_problem.estimate_error_output(
                    )
                    elapsed_error_estimator_output = reduced_timer.stop()

                    truth_timer.start()
                    self.reduced_problem.compute_relative_error_output(
                        **kwargs)
                    elapsed_relative_error_output = truth_timer.stop()

                    reduced_timer.start()
                    relative_error_estimator_output = self.reduced_problem.estimate_relative_error_output(
                    )
                    elapsed_relative_error_estimator_output = reduced_timer.stop(
                    )

                    if solution is not NotImplemented:
                        speedup_analysis_table[
                            "speedup_solve", n_int,
                            mu_index] = elapsed_truth_solve / elapsed_reduced_solve
                    else:
                        speedup_analysis_table["speedup_solve", n_int,
                                               mu_index] = NotImplemented
                    if error_estimator is not NotImplemented:
                        speedup_analysis_table[
                            "speedup_solve_and_estimate_error", n_int,
                            mu_index] = (elapsed_truth_solve + elapsed_error
                                         ) / (elapsed_reduced_solve +
                                              elapsed_error_estimator)
                    else:
                        speedup_analysis_table[
                            "speedup_solve_and_estimate_error", n_int,
                            mu_index] = NotImplemented
                    if relative_error_estimator is not NotImplemented:
                        speedup_analysis_table[
                            "speedup_solve_and_estimate_relative_error", n_int,
                            mu_index] = (elapsed_truth_solve +
                                         elapsed_relative_error) / (
                                             elapsed_reduced_solve +
                                             elapsed_relative_error_estimator)
                    else:
                        speedup_analysis_table[
                            "speedup_solve_and_estimate_relative_error", n_int,
                            mu_index] = NotImplemented
                    if output is not NotImplemented:
                        speedup_analysis_table[
                            "speedup_output", n_int,
                            mu_index] = (elapsed_truth_solve +
                                         elapsed_truth_output) / (
                                             elapsed_reduced_solve +
                                             elapsed_reduced_output)
                    else:
                        speedup_analysis_table["speedup_output", n_int,
                                               mu_index] = NotImplemented
                    if error_estimator_output is not NotImplemented:
                        assert output is not NotImplemented
                        speedup_analysis_table[
                            "speedup_output_and_estimate_error_output", n_int,
                            mu_index] = (elapsed_truth_solve +
                                         elapsed_truth_output +
                                         elapsed_error_output) / (
                                             elapsed_reduced_solve +
                                             elapsed_reduced_output +
                                             elapsed_error_estimator_output)
                    else:
                        speedup_analysis_table[
                            "speedup_output_and_estimate_error_output", n_int,
                            mu_index] = NotImplemented
                    if relative_error_estimator_output is not NotImplemented:
                        assert output is not NotImplemented
                        speedup_analysis_table[
                            "speedup_output_and_estimate_relative_error_output",
                            n_int, mu_index] = (
                                elapsed_truth_solve + elapsed_truth_output +
                                elapsed_relative_error_output) / (
                                    elapsed_reduced_solve +
                                    elapsed_reduced_output +
                                    elapsed_relative_error_estimator_output)
                    else:
                        speedup_analysis_table[
                            "speedup_output_and_estimate_relative_error_output",
                            n_int, mu_index] = NotImplemented

            # Print
            print("")
            print(speedup_analysis_table)

            print("")
            print(
                TextBox(self.truth_problem.name() + " " + self.label +
                        " speedup analysis ends",
                        fill="="))
            print("")

            # Export speedup analysis table
            speedup_analysis_table.save(
                self.folder["speedup_analysis"],
                "speedup_analysis" if filename is None else filename)
Beispiel #8
0
class SCMApproximationReductionMethod(ReductionMethod):
    
    # Default initialization of members
    def __init__(self, SCM_approximation, folder_prefix):
        # Call the parent initialization
        ReductionMethod.__init__(self, folder_prefix)
        
        # $$ OFFLINE DATA STRUCTURES $$ #
        # High fidelity problem
        self.SCM_approximation = SCM_approximation
        # I/O
        self.folder["post_processing"] = os.path.join(self.folder_prefix, "post_processing")
        self.greedy_selected_parameters = SCM_approximation.greedy_selected_parameters
        self.greedy_error_estimators = GreedyErrorEstimatorsList()
        
        # Get data that were temporarily store in the SCM_approximation
        self.bounding_box_minimum_eigensolver_parameters = self.SCM_approximation._input_storage_for_SCM_reduction["bounding_box_minimum_eigensolver_parameters"]
        self.bounding_box_maximum_eigensolver_parameters = self.SCM_approximation._input_storage_for_SCM_reduction["bounding_box_maximum_eigensolver_parameters"]
        del self.SCM_approximation._input_storage_for_SCM_reduction

    # OFFLINE: set the elements in the training set.
    def initialize_training_set(self, ntrain, enable_import=True, sampling=None, **kwargs):
        assert enable_import
        import_successful = ReductionMethod.initialize_training_set(self, self.SCM_approximation.mu_range, ntrain, enable_import, sampling, **kwargs)
        self.SCM_approximation.training_set = self.training_set
        return import_successful
        
    def initialize_testing_set(self, ntest, enable_import=False, sampling=None, **kwargs):
        return ReductionMethod.initialize_testing_set(self, self.SCM_approximation.mu_range, ntest, enable_import, sampling, **kwargs)
        
    # Perform the offline phase of SCM
    def offline(self):
        need_to_do_offline_stage = self._init_offline()
        if need_to_do_offline_stage:
            self._offline()
        self._finalize_offline()
        return self.SCM_approximation
    
    # Initialize data structures required for the offline phase
    def _init_offline(self):
        # Prepare folders and init SCM approximation
        all_folders = Folders()
        all_folders.update(self.folder)
        all_folders.update(self.SCM_approximation.folder)
        all_folders.pop("testing_set") # this is required only in the error/speedup analysis
        all_folders.pop("error_analysis") # this is required only in the error analysis
        all_folders.pop("speedup_analysis") # this is required only in the speedup analysis
        at_least_one_folder_created = all_folders.create()
        if not at_least_one_folder_created:
            return False # offline construction should be skipped, since data are already available
        else:
            self.SCM_approximation.init("offline")
            return True # offline construction should be carried out
            
    def _offline(self):
        print(TextBox("SCM offline phase begins", fill="="))
        print("")
        
        # Compute the bounding box \mathcal{B}
        self.compute_bounding_box()
        print("")
        
        # Arbitrarily start from the first parameter in the training set
        self.SCM_approximation.set_mu(self.training_set[0])
        relative_error_estimator_max = 2.*self.tol
        
        while self.SCM_approximation.N < self.Nmax and relative_error_estimator_max >= self.tol:
            print(TextLine("SCM N = " + str(self.SCM_approximation.N), fill="~"))
            
            # Store the greedy parameter
            self.store_greedy_selected_parameters()
            
            # Evaluate the coercivity constant
            print("evaluate the stability factor for mu =", self.SCM_approximation.mu)
            (alpha, eigenvector) = self.SCM_approximation.evaluate_stability_factor()
            print("stability factor =", alpha)
            
            # Update data structures related to upper bound vectors
            UB_vector = self.compute_UB_vector(eigenvector)
            self.update_UB_vectors(UB_vector)
            
            # Prepare for next iteration
            print("find next mu")
            (error_estimator_max, relative_error_estimator_max) = self.greedy()
            print("maximum SCM error estimator =", error_estimator_max)
            print("maximum SCM relative error estimator =", relative_error_estimator_max)
            
            print("")
            
        print(TextBox("SCM offline phase ends", fill="="))
        print("")
        
    # Finalize data structures required after the offline phase
    def _finalize_offline(self):
        self.SCM_approximation.init("online")
        
    # Compute the bounding box \mathcal{B}
    def compute_bounding_box(self):
        # Resize the bounding box storage
        Q = self.SCM_approximation.truth_problem.Q["a"]
        
        for q in range(Q):
            # Compute the minimum eigenvalue
            minimum_eigenvalue_calculator = ParametrizedCoercivityConstantEigenProblem(self.SCM_approximation.truth_problem, ("a", q), False, "smallest", self.bounding_box_minimum_eigensolver_parameters, self.folder_prefix)
            minimum_eigenvalue_calculator.init()
            (self.SCM_approximation.B_min[q], _) = minimum_eigenvalue_calculator.solve()
            print("B_min[" + str(q) + "] = " + str(self.SCM_approximation.B_min[q]))
            
            # Compute the maximum eigenvalue
            maximum_eigenvalue_calculator = ParametrizedCoercivityConstantEigenProblem(self.SCM_approximation.truth_problem, ("a", q), False, "largest", self.bounding_box_maximum_eigensolver_parameters, self.folder_prefix)
            maximum_eigenvalue_calculator.init()
            (self.SCM_approximation.B_max[q], _) = maximum_eigenvalue_calculator.solve()
            print("B_max[" + str(q) + "] = " + str(self.SCM_approximation.B_max[q]))
        
        # Save to file
        self.SCM_approximation.B_min.save(self.SCM_approximation.folder["reduced_operators"], "B_min")
        self.SCM_approximation.B_max.save(self.SCM_approximation.folder["reduced_operators"], "B_max")
        
    # Store the greedy parameter
    def store_greedy_selected_parameters(self):
        mu = self.SCM_approximation.mu
        
        self.SCM_approximation.greedy_selected_parameters.append(mu)
        self.SCM_approximation.N = len(self.SCM_approximation.greedy_selected_parameters)
        
        # Save to file
        self.SCM_approximation.greedy_selected_parameters.save(self.SCM_approximation.folder["reduced_operators"], "greedy_selected_parameters")
        
    # Compute the ratio between a_q(u,u) and s(u,u), for all q in vec
    def compute_UB_vector(self, u):
        Q = self.SCM_approximation.truth_problem.Q["a"]
        inner_product = self.SCM_approximation.truth_problem.inner_product[0]
        UB_vector = OnlineVector(Q)
        norm_S_squared = transpose(u)*inner_product*u
        for q in range(Q):
            A_q = self.SCM_approximation.truth_problem.operator["a"][q]
            UB_vector[q] = (transpose(u)*A_q*u)/norm_S_squared
        return UB_vector
        
    def update_UB_vectors(self, UB_vector):
        self.SCM_approximation.UB_vectors.append(UB_vector)
        self.SCM_approximation.UB_vectors.save(self.SCM_approximation.folder["reduced_operators"], "UB_vectors")
        
    # Choose the next parameter in the offline stage in a greedy fashion
    def greedy(self):
        def solve_and_estimate_error(mu):
            self.SCM_approximation.set_mu(mu)
            
            LB = self.SCM_approximation.get_stability_factor_lower_bound()
            UB = self.SCM_approximation.get_stability_factor_upper_bound()
            error_estimator = (UB - LB)/UB
            
            if LB/UB < 0 and not isclose(LB/UB, 0.): # if LB/UB << 0
                print("SCM warning at mu = " + str(mu) + ": LB = " + str(LB) + " < 0")
            if LB/UB > 1 and not isclose(LB/UB, 1.): # if LB/UB >> 1
                print("SCM warning at mu = " + str(mu) + ": LB = " + str(LB) + " > UB = " + str(UB))
                
            return error_estimator
            
        (error_estimator_max, error_estimator_argmax) = self.training_set.max(solve_and_estimate_error)
        self.SCM_approximation.set_mu(self.training_set[error_estimator_argmax])
        self.greedy_error_estimators.append(error_estimator_max)
        self.greedy_error_estimators.save(self.folder["post_processing"], "error_estimator_max")
        return (error_estimator_max, error_estimator_max/self.greedy_error_estimators[0])
        
    # Initialize data structures required for the error analysis phase
    def _init_error_analysis(self, **kwargs):
        # Initialize the exact coercivity constant object
        self.SCM_approximation.exact_coercivity_constant_calculator.init()
        
        # Initialize reduced order data structures in the SCM online problem
        self.SCM_approximation.init("online")
    
    # Compute the error of the scm approximation with respect to the
    # exact coercivity over the testing set
    def error_analysis(self, N_generator=None, filename=None, **kwargs):
        assert len(kwargs) == 0 # not used in this method
        
        self._init_error_analysis(**kwargs)
        self._error_analysis(N_generator, filename, **kwargs)
        self._finalize_error_analysis(**kwargs)
        
    def _error_analysis(self, N_generator=None, filename=None, **kwargs):
        if N_generator is None:
            def N_generator(n):
                return n
                
        N = self.SCM_approximation.N
        
        print(TextBox("SCM error analysis begins", fill="="))
        print("")
        
        error_analysis_table = ErrorAnalysisTable(self.testing_set)
        error_analysis_table.set_Nmax(N)
        error_analysis_table.add_column("normalized_error", group_name="scm", operations=("min", "mean", "max"))
        
        for (mu_index, mu) in enumerate(self.testing_set):
            print(TextLine("SCM " + str(mu_index), fill="~"))
            
            self.SCM_approximation.set_mu(mu)
            
            (exact, _) = self.SCM_approximation.evaluate_stability_factor()
            for n in range(1, N + 1): # n = 1, ... N
                n_arg = N_generator(n)
                
                if n_arg is not None:
                    LB = self.SCM_approximation.get_stability_factor_lower_bound(n_arg)
                    UB = self.SCM_approximation.get_stability_factor_upper_bound(n_arg)
                    
                    if LB/UB < 0 and not isclose(LB/UB, 0.): # if LB/UB << 0
                        print("SCM warning at mu = " + str(mu) + ": LB = " + str(LB) + " < 0")
                    if LB/UB > 1 and not isclose(LB/UB, 1.): # if LB/UB >> 1
                        print("SCM warning at mu = " + str(mu) + ": LB = " + str(LB) + " > UB = " + str(UB))
                    if LB/exact > 1 and not isclose(LB/exact, 1.): # if LB/exact >> 1
                        print("SCM warning at mu = " + str(mu) + ": LB = " + str(LB) + " > exact =" + str(exact))
                    
                    error_analysis_table["normalized_error", n, mu_index] = (exact - LB)/UB
                else:
                    error_analysis_table["normalized_error", n, mu_index] = NotImplemented
        
        # Print
        print("")
        print(error_analysis_table)
        
        print("")
        print(TextBox("SCM error analysis ends", fill="="))
        print("")
        
        # Export error analysis table
        error_analysis_table.save(self.folder["error_analysis"], "error_analysis" if filename is None else filename)
        
    # Compute the speedup of the scm approximation with respect to the
    # exact coercivity over the testing set
    def speedup_analysis(self, N_generator=None, filename=None, **kwargs):
        assert len(kwargs) == 0 # not used in this method
            
        self._init_speedup_analysis(**kwargs)
        self._speedup_analysis(N_generator, filename, **kwargs)
        self._finalize_speedup_analysis(**kwargs)
        
    # Initialize data structures required for the speedup analysis phase
    def _init_speedup_analysis(self, **kwargs):
        # Make sure to clean up snapshot cache to ensure that parametrized
        # expression evaluation is actually carried out
        self.SCM_approximation._alpha_LB_cache.clear()
        self.SCM_approximation._alpha_UB_cache.clear()
        self.SCM_approximation.exact_coercivity_constant_calculator._eigenvalue_cache.clear()
        self.SCM_approximation.exact_coercivity_constant_calculator._eigenvector_cache.clear()
        
    def _speedup_analysis(self, N_generator=None, filename=None, **kwargs):
        if N_generator is None:
            def N_generator(n):
                return n
                
        N = self.SCM_approximation.N
                
        print(TextBox("SCM speedup analysis begins", fill="="))
        print("")
        
        speedup_analysis_table = SpeedupAnalysisTable(self.testing_set)
        speedup_analysis_table.set_Nmax(N)
        speedup_analysis_table.add_column("speedup", group_name="speedup", operations=("min", "mean", "max"))
        
        exact_timer = Timer("parallel")
        SCM_timer = Timer("serial")
        
        for (mu_index, mu) in enumerate(self.testing_set):
            print(TextLine("SCM " + str(mu_index), fill="~"))
            
            self.SCM_approximation.set_mu(mu)
            
            exact_timer.start()
            self.SCM_approximation.evaluate_stability_factor()
            elapsed_exact = exact_timer.stop()
            
            for n in range(1, N + 1): # n = 1, ... N
                n_arg = N_generator(n)
                
                if n_arg is not None:
                    SCM_timer.start()
                    self.SCM_approximation.get_stability_factor_lower_bound(n_arg)
                    self.SCM_approximation.get_stability_factor_upper_bound(n_arg)
                    elapsed_SCM = SCM_timer.stop()
                    speedup_analysis_table["speedup", n, mu_index] = elapsed_exact/elapsed_SCM
                else:
                    speedup_analysis_table["speedup", n, mu_index] = NotImplemented
        
        # Print
        print("")
        print(speedup_analysis_table)
        
        print("")
        print(TextBox("SCM speedup analysis ends", fill="="))
        print("")
        
        # Export speedup analysis table
        speedup_analysis_table.save(self.folder["speedup_analysis"], "speedup_analysis" if filename is None else filename)
Beispiel #9
0
    class RBReduction_Class(DifferentialProblemReductionMethod_DerivedClass):
        """
        The folders used to store the snapshots and for the post processing data, the parameters for the greedy algorithm and the error estimator evaluations are initialized.
        
        :param truth_problem: class of the truth problem to be solved.
        :return: reduced RB class.
       
        """
        def __init__(self, truth_problem, **kwargs):
            # Call the parent initialization
            DifferentialProblemReductionMethod_DerivedClass.__init__(
                self, truth_problem, **kwargs)

            # Declare a GS object
            self.GS = None  # GramSchmidt (for problems with one component) or dict of GramSchmidt (for problem with several components)
            # I/O
            self.folder["snapshots"] = os.path.join(self.folder_prefix,
                                                    "snapshots")
            self.folder["post_processing"] = os.path.join(
                self.folder_prefix, "post_processing")
            self.greedy_selected_parameters = GreedySelectedParametersList()
            self.greedy_error_estimators = GreedyErrorEstimatorsList()
            self.label = "RB"

        def _init_offline(self):
            # Call parent to initialize inner product and reduced problem
            output = DifferentialProblemReductionMethod_DerivedClass._init_offline(
                self)

            # Declare a new GS for each basis component
            if len(self.truth_problem.components) > 1:
                self.GS = dict()
                for component in self.truth_problem.components:
                    assert len(
                        self.truth_problem.inner_product[component]) == 1
                    inner_product = self.truth_problem.inner_product[
                        component][0]
                    self.GS[component] = GramSchmidt(inner_product)
            else:
                assert len(self.truth_problem.inner_product) == 1
                inner_product = self.truth_problem.inner_product[0]
                self.GS = GramSchmidt(inner_product)

            # The current value of mu may have been already used when computing lifting functions.
            # If so, we do not want to use that value again at the first greedy iteration, because
            # for steady linear problems with only one paremtrized BC the resulting first snapshot
            # would have been already stored in the basis, being exactly equal to the lifting.
            # To this end, we arbitrarily change the current value of mu to the first parameter
            # in the training set.
            if output:  # do not bother changing current mu if offline stage has been already completed
                need_to_change_mu = False
                if len(self.truth_problem.components) > 1:
                    for component in self.truth_problem.components:
                        if self.reduced_problem.dirichlet_bc[
                                component] and not self.reduced_problem.dirichlet_bc_are_homogeneous[
                                    component]:
                            need_to_change_mu = True
                            break
                else:
                    if self.reduced_problem.dirichlet_bc and not self.reduced_problem.dirichlet_bc_are_homogeneous:
                        need_to_change_mu = True
                if (need_to_change_mu and len(
                        self.truth_problem.mu
                ) > 0  # there is not much we can change in the trivial case without any parameter!
                    ):
                    new_mu = self.training_set[0]
                    assert self.truth_problem.mu != new_mu
                    self.truth_problem.set_mu(new_mu)

            # Return
            return output

        def offline(self):
            """
            It performs the offline phase of the reduced order model.
            
            :return: reduced_problem where all offline data are stored.
            """
            need_to_do_offline_stage = self._init_offline()
            if need_to_do_offline_stage:
                self._offline()
            self._finalize_offline()
            return self.reduced_problem

        def _offline(self):
            print(
                TextBox(self.truth_problem.name() + " " + self.label +
                        " offline phase begins",
                        fill="="))
            print("")

            iteration = 0
            relative_error_estimator_max = 2. * self.tol
            while self.reduced_problem.N < self.Nmax and relative_error_estimator_max >= self.tol:
                print(TextLine("N = " + str(self.reduced_problem.N), fill="#"))

                print("truth solve for mu =", self.truth_problem.mu)
                snapshot = self.truth_problem.solve()
                self.truth_problem.export_solution(self.folder["snapshots"],
                                                   "truth_" + str(iteration),
                                                   snapshot)
                snapshot = self.postprocess_snapshot(snapshot, iteration)

                print("update basis matrix")
                self.update_basis_matrix(snapshot)
                iteration += 1

                print("build reduced operators")
                self.reduced_problem.build_reduced_operators()

                print("reduced order solve")
                self.reduced_problem.solve()

                print("build operators for error estimation")
                self.reduced_problem.build_error_estimation_operators()

                (absolute_error_estimator_max,
                 relative_error_estimator_max) = self.greedy()
                print("maximum absolute error estimator over training set =",
                      absolute_error_estimator_max)
                print("maximum relative error estimator over training set =",
                      relative_error_estimator_max)

                print("")

            print(
                TextBox(self.truth_problem.name() + " " + self.label +
                        " offline phase ends",
                        fill="="))
            print("")

        def update_basis_matrix(self, snapshot):
            """
            It updates basis matrix.
            
            :param snapshot: last offline solution calculated.
            """
            if len(self.truth_problem.components) > 1:
                for component in self.truth_problem.components:
                    self.reduced_problem.basis_functions.enrich(
                        snapshot, component=component)
                    self.GS[component].apply(
                        self.reduced_problem.basis_functions[component],
                        self.reduced_problem.N_bc[component])
                    self.reduced_problem.N[component] += 1
                self.reduced_problem.basis_functions.save(
                    self.reduced_problem.folder["basis"], "basis")
            else:
                self.reduced_problem.basis_functions.enrich(snapshot)
                self.GS.apply(self.reduced_problem.basis_functions,
                              self.reduced_problem.N_bc)
                self.reduced_problem.N += 1
                self.reduced_problem.basis_functions.save(
                    self.reduced_problem.folder["basis"], "basis")

        def greedy(self):
            """
            It chooses the next parameter in the offline stage in a greedy fashion: wrapper with post processing of the result (in particular, set greedily selected parameter and save to file)
            
            :return: max error estimator and the comparison with the first one calculated.
            """
            (error_estimator_max, error_estimator_argmax) = self._greedy()
            self.truth_problem.set_mu(
                self.training_set[error_estimator_argmax])
            self.greedy_selected_parameters.append(
                self.training_set[error_estimator_argmax])
            self.greedy_selected_parameters.save(
                self.folder["post_processing"], "mu_greedy")
            self.greedy_error_estimators.append(error_estimator_max)
            self.greedy_error_estimators.save(self.folder["post_processing"],
                                              "error_estimator_max")
            return (error_estimator_max,
                    error_estimator_max / self.greedy_error_estimators[0])

        def _greedy(self):
            """
            It chooses the next parameter in the offline stage in a greedy fashion. Internal method.
            
            :return: max error estimator and the respective parameter.
            """

            # Print some additional information on the consistency of the reduced basis
            print("absolute error for current mu =",
                  self.reduced_problem.compute_error())
            print("absolute error estimator for current mu =",
                  self.reduced_problem.estimate_error())

            # Carry out the actual greedy search
            def solve_and_estimate_error(mu):
                self.reduced_problem.set_mu(mu)
                self.reduced_problem.solve()
                error_estimator = self.reduced_problem.estimate_error()
                log(
                    DEBUG, "Error estimator for mu = " + str(mu) + " is " +
                    str(error_estimator))
                return error_estimator

            print("find next mu")
            return self.training_set.max(solve_and_estimate_error)

        def error_analysis(self, N_generator=None, filename=None, **kwargs):
            """
            It computes the error of the reduced order approximation with respect to the full order one over the testing set.
            
            :param N: dimension of reduced problem.
            """
            self._init_error_analysis(**kwargs)
            self._error_analysis(N_generator, filename, **kwargs)
            self._finalize_error_analysis(**kwargs)

        def _error_analysis(self, N_generator=None, filename=None, **kwargs):
            if N_generator is None:

                def N_generator(n):
                    return n

            if "components" in kwargs:
                components = kwargs["components"]
            else:
                components = self.truth_problem.components

            N = self.reduced_problem.N
            if isinstance(N, dict):
                N = min(N.values())

            print(
                TextBox(self.truth_problem.name() + " " + self.label +
                        " error analysis begins",
                        fill="="))
            print("")

            error_analysis_table = ErrorAnalysisTable(self.testing_set)
            error_analysis_table.set_Nmax(N)
            if len(components) > 1:
                all_components_string = "".join(components)
                for component in components:
                    error_analysis_table.add_column("error_" + component,
                                                    group_name="solution_" +
                                                    component + "_error",
                                                    operations=("mean", "max"))
                    error_analysis_table.add_column(
                        "relative_error_" + component,
                        group_name="solution_" + component + "_relative_error",
                        operations=("mean", "max"))
                error_analysis_table.add_column(
                    "error_" + all_components_string,
                    group_name="solution_" + all_components_string + "_error",
                    operations=("mean", "max"))
                error_analysis_table.add_column(
                    "error_estimator_" + all_components_string,
                    group_name="solution_" + all_components_string + "_error",
                    operations=("mean", "max"))
                error_analysis_table.add_column(
                    "effectivity_" + all_components_string,
                    group_name="solution_" + all_components_string + "_error",
                    operations=("min", "mean", "max"))
                error_analysis_table.add_column(
                    "relative_error_" + all_components_string,
                    group_name="solution_" + all_components_string +
                    "_relative_error",
                    operations=("mean", "max"))
                error_analysis_table.add_column(
                    "relative_error_estimator_" + all_components_string,
                    group_name="solution_" + all_components_string +
                    "_relative_error",
                    operations=("mean", "max"))
                error_analysis_table.add_column(
                    "relative_effectivity_" + all_components_string,
                    group_name="solution_" + all_components_string +
                    "_relative_error",
                    operations=("min", "mean", "max"))
            else:
                component = components[0]
                error_analysis_table.add_column("error_" + component,
                                                group_name="solution_" +
                                                component + "_error",
                                                operations=("mean", "max"))
                error_analysis_table.add_column("error_estimator_" + component,
                                                group_name="solution_" +
                                                component + "_error",
                                                operations=("mean", "max"))
                error_analysis_table.add_column(
                    "effectivity_" + component,
                    group_name="solution_" + component + "_error",
                    operations=("min", "mean", "max"))
                error_analysis_table.add_column("relative_error_" + component,
                                                group_name="solution_" +
                                                component + "_relative_error",
                                                operations=("mean", "max"))
                error_analysis_table.add_column(
                    "relative_error_estimator_" + component,
                    group_name="solution_" + component + "_relative_error",
                    operations=("mean", "max"))
                error_analysis_table.add_column(
                    "relative_effectivity_" + component,
                    group_name="solution_" + component + "_relative_error",
                    operations=("min", "mean", "max"))
            error_analysis_table.add_column("error_output",
                                            group_name="output_error",
                                            operations=("mean", "max"))
            error_analysis_table.add_column("error_estimator_output",
                                            group_name="output_error",
                                            operations=("mean", "max"))
            error_analysis_table.add_column("effectivity_output",
                                            group_name="output_error",
                                            operations=("min", "mean", "max"))
            error_analysis_table.add_column("relative_error_output",
                                            group_name="output_relative_error",
                                            operations=("mean", "max"))
            error_analysis_table.add_column("relative_error_estimator_output",
                                            group_name="output_relative_error",
                                            operations=("mean", "max"))
            error_analysis_table.add_column("relative_effectivity_output",
                                            group_name="output_relative_error",
                                            operations=("min", "mean", "max"))

            for (mu_index, mu) in enumerate(self.testing_set):
                print(TextLine(str(mu_index), fill="#"))

                self.reduced_problem.set_mu(mu)

                for n in range(1, N + 1):  # n = 1, ... N
                    n_arg = N_generator(n)

                    if n_arg is not None:
                        self.reduced_problem.solve(n_arg, **kwargs)
                        error = self.reduced_problem.compute_error(**kwargs)
                        if len(components) > 1:
                            error[all_components_string] = sqrt(
                                sum([
                                    error[component]**2
                                    for component in components
                                ]))
                        error_estimator = self.reduced_problem.estimate_error()
                        relative_error = self.reduced_problem.compute_relative_error(
                            **kwargs)
                        if len(components) > 1:
                            relative_error[all_components_string] = sqrt(
                                sum([
                                    relative_error[component]**2
                                    for component in components
                                ]))
                        relative_error_estimator = self.reduced_problem.estimate_relative_error(
                        )

                        self.reduced_problem.compute_output()
                        error_output = self.reduced_problem.compute_error_output(
                            **kwargs)
                        error_output_estimator = self.reduced_problem.estimate_error_output(
                        )
                        relative_error_output = self.reduced_problem.compute_relative_error_output(
                            **kwargs)
                        relative_error_output_estimator = self.reduced_problem.estimate_relative_error_output(
                        )
                    else:
                        if len(components) > 1:
                            error = {
                                component: NotImplemented
                                for component in components
                            }
                            error[all_components_string] = NotImplemented
                        else:
                            error = NotImplemented
                        error_estimator = NotImplemented
                        if len(components) > 1:
                            relative_error = {
                                component: NotImplemented
                                for component in components
                            }
                            relative_error[
                                all_components_string] = NotImplemented
                        else:
                            relative_error = NotImplemented
                        relative_error_estimator = NotImplemented

                        error_output = NotImplemented
                        error_output_estimator = NotImplemented
                        relative_error_output = NotImplemented
                        relative_error_output_estimator = NotImplemented

                    if len(components) > 1:
                        for component in components:
                            error_analysis_table["error_" + component, n,
                                                 mu_index] = error[component]
                            error_analysis_table[
                                "relative_error_" + component, n,
                                mu_index] = relative_error[component]
                        error_analysis_table[
                            "error_" + all_components_string, n,
                            mu_index] = error[all_components_string]
                        error_analysis_table["error_estimator_" +
                                             all_components_string, n,
                                             mu_index] = error_estimator
                        error_analysis_table[
                            "effectivity_" + all_components_string, n,
                            mu_index] = error_analysis_table[
                                "error_estimator_" + all_components_string, n,
                                mu_index] / error_analysis_table[
                                    "error_" + all_components_string, n,
                                    mu_index]
                        error_analysis_table[
                            "relative_error_" + all_components_string, n,
                            mu_index] = relative_error[all_components_string]
                        error_analysis_table[
                            "relative_error_estimator_" +
                            all_components_string, n,
                            mu_index] = relative_error_estimator
                        error_analysis_table[
                            "relative_effectivity_" + all_components_string, n,
                            mu_index] = error_analysis_table[
                                "relative_error_estimator_" +
                                all_components_string, n,
                                mu_index] / error_analysis_table[
                                    "relative_error_" + all_components_string,
                                    n, mu_index]
                    else:
                        component = components[0]
                        error_analysis_table["error_" + component, n,
                                             mu_index] = error
                        error_analysis_table["error_estimator_" + component, n,
                                             mu_index] = error_estimator
                        error_analysis_table[
                            "effectivity_" + component, n,
                            mu_index] = error_analysis_table[
                                "error_estimator_" + component, n,
                                mu_index] / error_analysis_table["error_" +
                                                                 component, n,
                                                                 mu_index]
                        error_analysis_table["relative_error_" + component, n,
                                             mu_index] = relative_error
                        error_analysis_table[
                            "relative_error_estimator_" + component, n,
                            mu_index] = relative_error_estimator
                        error_analysis_table[
                            "relative_effectivity_" + component, n,
                            mu_index] = error_analysis_table[
                                "relative_error_estimator_" + component, n,
                                mu_index] / error_analysis_table[
                                    "relative_error_" + component, n, mu_index]

                    error_analysis_table["error_output", n,
                                         mu_index] = error_output
                    error_analysis_table["error_estimator_output", n,
                                         mu_index] = error_output_estimator
                    error_analysis_table["effectivity_output", n,
                                         mu_index] = error_analysis_table[
                                             "error_estimator_output", n,
                                             mu_index] / error_analysis_table[
                                                 "error_output", n, mu_index]
                    error_analysis_table["relative_error_output", n,
                                         mu_index] = relative_error_output
                    error_analysis_table[
                        "relative_error_estimator_output", n,
                        mu_index] = relative_error_output_estimator
                    error_analysis_table[
                        "relative_effectivity_output", n,
                        mu_index] = error_analysis_table[
                            "relative_error_estimator_output", n,
                            mu_index] / error_analysis_table[
                                "relative_error_output", n, mu_index]

            # Print
            print("")
            print(error_analysis_table)

            print("")
            print(
                TextBox(self.truth_problem.name() + " " + self.label +
                        " error analysis ends",
                        fill="="))
            print("")

            # Export error analysis table
            error_analysis_table.save(
                self.folder["error_analysis"],
                "error_analysis" if filename is None else filename)

        def speedup_analysis(self, N_generator=None, filename=None, **kwargs):
            """
            It computes the speedup of the reduced order approximation with respect to the full order one over the testing set.
            
            :param N: dimension of the reduced problem.
            """
            self._init_speedup_analysis(**kwargs)
            self._speedup_analysis(N_generator, filename, **kwargs)
            self._finalize_speedup_analysis(**kwargs)

        def _speedup_analysis(self, N_generator=None, filename=None, **kwargs):
            if N_generator is None:

                def N_generator(n):
                    return n

            N = self.reduced_problem.N
            if isinstance(N, dict):
                N = min(N.values())

            print(
                TextBox(self.truth_problem.name() + " " + self.label +
                        " speedup analysis begins",
                        fill="="))
            print("")

            speedup_analysis_table = SpeedupAnalysisTable(self.testing_set)
            speedup_analysis_table.set_Nmax(N)
            speedup_analysis_table.add_column("speedup_solve",
                                              group_name="speedup_solve",
                                              operations=("min", "mean",
                                                          "max"))
            speedup_analysis_table.add_column(
                "speedup_solve_and_estimate_error",
                group_name="speedup_solve_and_estimate_error",
                operations=("min", "mean", "max"))
            speedup_analysis_table.add_column(
                "speedup_solve_and_estimate_relative_error",
                group_name="speedup_solve_and_estimate_relative_error",
                operations=("min", "mean", "max"))
            speedup_analysis_table.add_column("speedup_output",
                                              group_name="speedup_output",
                                              operations=("min", "mean",
                                                          "max"))
            speedup_analysis_table.add_column(
                "speedup_output_and_estimate_error_output",
                group_name="speedup_output_and_estimate_error_output",
                operations=("min", "mean", "max"))
            speedup_analysis_table.add_column(
                "speedup_output_and_estimate_relative_error_output",
                group_name="speedup_output_and_estimate_relative_error_output",
                operations=("min", "mean", "max"))

            truth_timer = Timer("parallel")
            reduced_timer = Timer("serial")

            for (mu_index, mu) in enumerate(self.testing_set):
                print(TextLine(str(mu_index), fill="#"))

                self.reduced_problem.set_mu(mu)

                truth_timer.start()
                self.truth_problem.solve(**kwargs)
                elapsed_truth_solve = truth_timer.stop()

                truth_timer.start()
                self.truth_problem.compute_output()
                elapsed_truth_output = truth_timer.stop()

                for n in range(1, N + 1):  # n = 1, ... N
                    n_arg = N_generator(n)

                    if n_arg is not None:
                        reduced_timer.start()
                        solution = self.reduced_problem.solve(n_arg, **kwargs)
                        elapsed_reduced_solve = reduced_timer.stop()

                        truth_timer.start()
                        self.reduced_problem.compute_error(**kwargs)
                        elapsed_error = truth_timer.stop()

                        reduced_timer.start()
                        error_estimator = self.reduced_problem.estimate_error()
                        elapsed_error_estimator = reduced_timer.stop()

                        truth_timer.start()
                        self.reduced_problem.compute_relative_error(**kwargs)
                        elapsed_relative_error = truth_timer.stop()

                        reduced_timer.start()
                        relative_error_estimator = self.reduced_problem.estimate_relative_error(
                        )
                        elapsed_relative_error_estimator = reduced_timer.stop()

                        reduced_timer.start()
                        output = self.reduced_problem.compute_output()
                        elapsed_reduced_output = reduced_timer.stop()

                        truth_timer.start()
                        self.reduced_problem.compute_error_output(**kwargs)
                        elapsed_error_output = truth_timer.stop()

                        reduced_timer.start()
                        error_estimator_output = self.reduced_problem.estimate_error_output(
                        )
                        elapsed_error_estimator_output = reduced_timer.stop()

                        truth_timer.start()
                        self.reduced_problem.compute_relative_error_output(
                            **kwargs)
                        elapsed_relative_error_output = truth_timer.stop()

                        reduced_timer.start()
                        relative_error_estimator_output = self.reduced_problem.estimate_relative_error_output(
                        )
                        elapsed_relative_error_estimator_output = reduced_timer.stop(
                        )
                    else:
                        solution = NotImplemented
                        error_estimator = NotImplemented
                        relative_error_estimator = NotImplemented

                        output = NotImplemented
                        error_estimator_output = NotImplemented
                        relative_error_estimator_output = NotImplemented

                    if solution is not NotImplemented:
                        speedup_analysis_table[
                            "speedup_solve", n,
                            mu_index] = elapsed_truth_solve / elapsed_reduced_solve
                    else:
                        speedup_analysis_table["speedup_solve", n,
                                               mu_index] = NotImplemented
                    if error_estimator is not NotImplemented:
                        speedup_analysis_table[
                            "speedup_solve_and_estimate_error", n,
                            mu_index] = (elapsed_truth_solve + elapsed_error
                                         ) / (elapsed_reduced_solve +
                                              elapsed_error_estimator)
                    else:
                        speedup_analysis_table[
                            "speedup_solve_and_estimate_error", n,
                            mu_index] = NotImplemented
                    if relative_error_estimator is not NotImplemented:
                        speedup_analysis_table[
                            "speedup_solve_and_estimate_relative_error", n,
                            mu_index] = (elapsed_truth_solve +
                                         elapsed_relative_error) / (
                                             elapsed_reduced_solve +
                                             elapsed_relative_error_estimator)
                    else:
                        speedup_analysis_table[
                            "speedup_solve_and_estimate_relative_error", n,
                            mu_index] = NotImplemented
                    if output is not NotImplemented:
                        speedup_analysis_table[
                            "speedup_output", n,
                            mu_index] = (elapsed_truth_solve +
                                         elapsed_truth_output) / (
                                             elapsed_reduced_solve +
                                             elapsed_reduced_output)
                    else:
                        speedup_analysis_table["speedup_output", n,
                                               mu_index] = NotImplemented
                    if error_estimator_output is not NotImplemented:
                        assert output is not NotImplemented
                        speedup_analysis_table[
                            "speedup_output_and_estimate_error_output", n,
                            mu_index] = (elapsed_truth_solve +
                                         elapsed_truth_output +
                                         elapsed_error_output) / (
                                             elapsed_reduced_solve +
                                             elapsed_reduced_output +
                                             elapsed_error_estimator_output)
                    else:
                        speedup_analysis_table[
                            "speedup_output_and_estimate_error_output", n,
                            mu_index] = NotImplemented
                    if relative_error_estimator_output is not NotImplemented:
                        assert output is not NotImplemented
                        speedup_analysis_table[
                            "speedup_output_and_estimate_relative_error_output",
                            n, mu_index] = (
                                elapsed_truth_solve + elapsed_truth_output +
                                elapsed_relative_error_output) / (
                                    elapsed_reduced_solve +
                                    elapsed_reduced_output +
                                    elapsed_relative_error_estimator_output)
                    else:
                        speedup_analysis_table[
                            "speedup_output_and_estimate_relative_error_output",
                            n, mu_index] = NotImplemented

            # Print
            print("")
            print(speedup_analysis_table)

            print("")
            print(
                TextBox(self.truth_problem.name() + " " + self.label +
                        " speedup analysis ends",
                        fill="="))
            print("")

            # Export speedup analysis table
            speedup_analysis_table.save(
                self.folder["speedup_analysis"],
                "speedup_analysis" if filename is None else filename)