Esempio n. 1
0
def extend_hierarchy(levels,
                     strength,
                     aggregate,
                     smooth,
                     improve_candidates,
                     diagonal_dominance=False,
                     keep=True):
    """Service routine to implement the strength of connection, aggregation,
    tentative prolongation construction, and prolongation smoothing.  Called by
    smoothed_aggregation_solver.
    """
    def unpack_arg(v):
        if isinstance(v, tuple):
            return v[0], v[1]
        else:
            return v, {}

    A = levels[-1].A
    B = levels[-1].B
    if A.symmetry == "nonsymmetric":
        AH = A.H.asformat(A.format)
        BH = levels[-1].BH

    ##
    # Compute the strength-of-connection matrix C, where larger
    # C[i,j] denote stronger couplings between i and j.
    fn, kwargs = unpack_arg(strength[len(levels) - 1])
    if fn == 'symmetric':
        C = symmetric_strength_of_connection(A, **kwargs)
    elif fn == 'classical':
        C = classical_strength_of_connection(A, **kwargs)
    elif fn == 'distance':
        C = distance_strength_of_connection(A, **kwargs)
    elif (fn == 'ode') or (fn == 'evolution'):
        if 'B' in kwargs:
            C = evolution_strength_of_connection(A, **kwargs)
        else:
            C = evolution_strength_of_connection(A, B, **kwargs)
    elif fn == 'energy_based':
        C = energy_based_strength_of_connection(A, **kwargs)
    elif fn == 'predefined':
        C = kwargs['C'].tocsr()
    elif fn == 'algebraic_distance':
        C = algebraic_distance(A, **kwargs)
    elif fn is None:
        C = A.tocsr()
    else:
        raise ValueError('unrecognized strength of connection method: %s' %
                         str(fn))

    ##
    # Avoid coarsening diagonally dominant rows
    flag, kwargs = unpack_arg(diagonal_dominance)
    if flag:
        C = eliminate_diag_dom_nodes(A, C, **kwargs)

    ##
    # Compute the aggregation matrix AggOp (i.e., the nodal coarsening of A).
    # AggOp is a boolean matrix, where the sparsity pattern for the k-th column
    # denotes the fine-grid nodes agglomerated into k-th coarse-grid node.
    fn, kwargs = unpack_arg(aggregate[len(levels) - 1])
    if fn == 'standard':
        AggOp = standard_aggregation(C, **kwargs)[0]
    elif fn == 'naive':
        AggOp = naive_aggregation(C, **kwargs)[0]
    elif fn == 'lloyd':
        AggOp = lloyd_aggregation(C, **kwargs)[0]
    elif fn == 'predefined':
        AggOp = kwargs['AggOp'].tocsr()
    else:
        raise ValueError('unrecognized aggregation method %s' % str(fn))

    ##
    # Improve near nullspace candidates by relaxing on A B = 0
    fn, kwargs = unpack_arg(improve_candidates[len(levels) - 1])
    if fn is not None:
        b = np.zeros((A.shape[0], 1), dtype=A.dtype)
        B = relaxation_as_linear_operator((fn, kwargs), A, b) * B
        levels[-1].B = B
        if A.symmetry == "nonsymmetric":
            BH = relaxation_as_linear_operator((fn, kwargs), AH, b) * BH
            levels[-1].BH = BH

    ##
    # Compute the tentative prolongator, T, which is a tentative interpolation
    # matrix from the coarse-grid to the fine-grid.  T exactly interpolates
    # B_fine = T B_coarse.
    T, B = fit_candidates(AggOp, B)
    if A.symmetry == "nonsymmetric":
        TH, BH = fit_candidates(AggOp, BH)

    ##
    # Smooth the tentative prolongator, so that it's accuracy is greatly
    # improved for algebraically smooth error.
    fn, kwargs = unpack_arg(smooth[len(levels) - 1])
    if fn == 'jacobi':
        P = jacobi_prolongation_smoother(A, T, C, B, **kwargs)
    elif fn == 'richardson':
        P = richardson_prolongation_smoother(A, T, **kwargs)
    elif fn == 'energy':
        P = energy_prolongation_smoother(A, T, C, B, None, (False, {}),
                                         **kwargs)
    elif fn is None:
        P = T
    else:
        raise ValueError('unrecognized prolongation smoother method %s' %
                         str(fn))

    ##
    # Compute the restriction matrix, R, which interpolates from the fine-grid
    # to the coarse-grid.  If A is nonsymmetric, then R must be constructed
    # based on A.H.  Otherwise R = P.H or P.T.
    symmetry = A.symmetry
    if symmetry == 'hermitian':
        R = P.H
    elif symmetry == 'symmetric':
        R = P.T
    elif symmetry == 'nonsymmetric':
        fn, kwargs = unpack_arg(smooth[len(levels) - 1])
        if fn == 'jacobi':
            R = jacobi_prolongation_smoother(AH, TH, C, BH, **kwargs).H
        elif fn == 'richardson':
            R = richardson_prolongation_smoother(AH, TH, **kwargs).H
        elif fn == 'energy':
            R = energy_prolongation_smoother(AH, TH, C, BH, None, (False, {}),
                                             **kwargs)
            R = R.H
        elif fn is None:
            R = T.H
        else:
            raise ValueError('unrecognized prolongation smoother method %s' %
                             str(fn))

    if keep:
        levels[-1].C = C  # strength of connection matrix
        levels[-1].AggOp = AggOp  # aggregation operator
        levels[-1].T = T  # tentative prolongator

    levels[-1].P = P  # smoothed prolongator
    levels[-1].R = R  # restriction operator

    levels.append(multilevel_solver.level())
    A = R * A * P  # Galerkin operator
    A.symmetry = symmetry
    levels[-1].A = A
    levels[-1].B = B  # right near nullspace candidates

    if A.symmetry == "nonsymmetric":
        levels[-1].BH = BH  # left near nullspace candidates
Esempio n. 2
0
def extend_hierarchy(levels, strength, aggregate, smooth, improve_candidates,
                     diagonal_dominance=False, keep=True):
    """Service routine to implement the strength of connection, aggregation,
    tentative prolongation construction, and prolongation smoothing.  Called by
    smoothed_aggregation_solver.
    """

    def unpack_arg(v):
        if isinstance(v, tuple):
            return v[0], v[1]
        else:
            return v, {}

    A = levels[-1].A
    B = levels[-1].B
    if A.symmetry == "nonsymmetric":
        AH = A.H.asformat(A.format)
        BH = levels[-1].BH

    # Compute the strength-of-connection matrix C, where larger
    # C[i,j] denote stronger couplings between i and j.
    fn, kwargs = unpack_arg(strength[len(levels)-1])
    if fn == 'symmetric':
        C = symmetric_strength_of_connection(A, **kwargs)
    elif fn == 'classical':
        C = classical_strength_of_connection(A, **kwargs)
    elif fn == 'distance':
        C = distance_strength_of_connection(A, **kwargs)
    elif (fn == 'ode') or (fn == 'evolution'):
        if 'B' in kwargs:
            C = evolution_strength_of_connection(A, **kwargs)
        else:
            C = evolution_strength_of_connection(A, B, **kwargs)
    elif fn == 'energy_based':
        C = energy_based_strength_of_connection(A, **kwargs)
    elif fn == 'predefined':
        C = kwargs['C'].tocsr()
    elif fn == 'algebraic_distance':
        C = algebraic_distance(A, **kwargs)
    elif fn is None:
        C = A.tocsr()
    else:
        raise ValueError('unrecognized strength of connection method: %s' %
                         str(fn))

    # Avoid coarsening diagonally dominant rows
    flag, kwargs = unpack_arg(diagonal_dominance)
    if flag:
        C = eliminate_diag_dom_nodes(A, C, **kwargs)

    # Compute the aggregation matrix AggOp (i.e., the nodal coarsening of A).
    # AggOp is a boolean matrix, where the sparsity pattern for the k-th column
    # denotes the fine-grid nodes agglomerated into k-th coarse-grid node.
    fn, kwargs = unpack_arg(aggregate[len(levels)-1])
    if fn == 'standard':
        AggOp = standard_aggregation(C, **kwargs)[0]
    elif fn == 'naive':
        AggOp = naive_aggregation(C, **kwargs)[0]
    elif fn == 'lloyd':
        AggOp = lloyd_aggregation(C, **kwargs)[0]
    elif fn == 'predefined':
        AggOp = kwargs['AggOp'].tocsr()
    else:
        raise ValueError('unrecognized aggregation method %s' % str(fn))

    # Improve near nullspace candidates by relaxing on A B = 0
    fn, kwargs = unpack_arg(improve_candidates[len(levels)-1])
    if fn is not None:
        b = np.zeros((A.shape[0], 1), dtype=A.dtype)
        B = relaxation_as_linear_operator((fn, kwargs), A, b) * B
        levels[-1].B = B
        if A.symmetry == "nonsymmetric":
            BH = relaxation_as_linear_operator((fn, kwargs), AH, b) * BH
            levels[-1].BH = BH

    # Compute the tentative prolongator, T, which is a tentative interpolation
    # matrix from the coarse-grid to the fine-grid.  T exactly interpolates
    # B_fine = T B_coarse.
    T, B = fit_candidates(AggOp, B)
    if A.symmetry == "nonsymmetric":
        TH, BH = fit_candidates(AggOp, BH)

    # Smooth the tentative prolongator, so that it's accuracy is greatly
    # improved for algebraically smooth error.
    fn, kwargs = unpack_arg(smooth[len(levels)-1])
    if fn == 'jacobi':
        P = jacobi_prolongation_smoother(A, T, C, B, **kwargs)
    elif fn == 'richardson':
        P = richardson_prolongation_smoother(A, T, **kwargs)
    elif fn == 'energy':
        P = energy_prolongation_smoother(A, T, C, B, None, (False, {}),
                                         **kwargs)
    elif fn is None:
        P = T
    else:
        raise ValueError('unrecognized prolongation smoother method %s' %
                         str(fn))

    # Compute the restriction matrix, R, which interpolates from the fine-grid
    # to the coarse-grid.  If A is nonsymmetric, then R must be constructed
    # based on A.H.  Otherwise R = P.H or P.T.
    symmetry = A.symmetry
    if symmetry == 'hermitian':
        R = P.H
    elif symmetry == 'symmetric':
        R = P.T
    elif symmetry == 'nonsymmetric':
        fn, kwargs = unpack_arg(smooth[len(levels)-1])
        if fn == 'jacobi':
            R = jacobi_prolongation_smoother(AH, TH, C, BH, **kwargs).H
        elif fn == 'richardson':
            R = richardson_prolongation_smoother(AH, TH, **kwargs).H
        elif fn == 'energy':
            R = energy_prolongation_smoother(AH, TH, C, BH, None, (False, {}),
                                             **kwargs)
            R = R.H
        elif fn is None:
            R = T.H
        else:
            raise ValueError('unrecognized prolongation smoother method %s' %
                             str(fn))

    if keep:
        levels[-1].C = C  # strength of connection matrix
        levels[-1].AggOp = AggOp  # aggregation operator
        levels[-1].T = T  # tentative prolongator

    levels[-1].P = P  # smoothed prolongator
    levels[-1].R = R  # restriction operator

    levels.append(multilevel_solver.level())
    A = R * A * P              # Galerkin operator
    A.symmetry = symmetry
    levels[-1].A = A
    levels[-1].B = B           # right near nullspace candidates

    if A.symmetry == "nonsymmetric":
        levels[-1].BH = BH     # left near nullspace candidates
Esempio n. 3
0
def extend_hierarchy(levels,
                     strength,
                     aggregate,
                     smooth,
                     improve_candidates,
                     diagonal_dominance=False,
                     keep=True):
    """Service routine to implement the strength of connection, aggregation,
    tentative prolongation construction, and prolongation smoothing.  Called by
    smoothed_aggregation_solver.
    """
    def unpack_arg(v):
        if isinstance(v, tuple):
            return v[0], v[1]
        else:
            return v, {}

    A = levels[-1].A
    B = levels[-1].B
    if A.symmetry == "nonsymmetric":
        AH = A.H.asformat(A.format)
        BH = levels[-1].BH

    ##
    # Compute the strength-of-connection matrix C, where larger
    # C[i,j] denote stronger couplings between i and j.
    fn, kwargs = unpack_arg(strength[len(levels) - 1])
    if fn == 'symmetric':
        C = symmetric_strength_of_connection(A, **kwargs)
    elif fn == 'classical':
        C = classical_strength_of_connection(A, **kwargs)
    elif fn == 'distance':
        C = distance_strength_of_connection(A, **kwargs)
    elif (fn == 'ode') or (fn == 'evolution'):
        if kwargs.has_key('B'):
            C = evolution_strength_of_connection(A, **kwargs)
        else:
            C = evolution_strength_of_connection(A, B, **kwargs)
    elif fn == 'energy_based':
        C = energy_based_strength_of_connection(A, **kwargs)
    elif fn == 'predefined':
        C = kwargs['C'].tocsr()
    elif fn == 'algebraic_distance':
        C = algebraic_distance(A, **kwargs)
    elif fn is None:
        C = A.tocsr()
    else:
        raise ValueError('unrecognized strength of connection method: %s' %
                         str(fn))

    ##
    # Avoid coarsening diagonally dominant rows
    flag, kwargs = unpack_arg(diagonal_dominance)
    if flag:
        C = eliminate_diag_dom_nodes(A, C, **kwargs)

    ##
    # Compute the aggregation matrix AggOp (i.e., the nodal coarsening of A).
    # AggOp is a boolean matrix, where the sparsity pattern for the k-th column
    # denotes the fine-grid nodes agglomerated into k-th coarse-grid node.
    fn, kwargs = unpack_arg(aggregate[len(levels) - 1])
    if fn == 'standard':
        AggOp, Cnodes = standard_aggregation(C, **kwargs)
    elif fn == 'naive':
        AggOp, Cnodes = naive_aggregation(C, **kwargs)
    elif fn == 'lloyd':
        AggOp, Cnodes = lloyd_aggregation(C, **kwargs)
    elif fn == 'predefined':
        AggOp = kwargs['AggOp'].tocsr()
        Cnodes = kwargs['Cnodes']
    else:
        raise ValueError('unrecognized aggregation method %s' % str(fn))

    ##
    # Improve near nullspace candidates by relaxing on A B = 0
    fn, kwargs = unpack_arg(improve_candidates[len(levels) - 1])
    if fn is not None:
        b = numpy.zeros((A.shape[0], 1), dtype=A.dtype)
        B = relaxation_as_linear_operator((fn, kwargs), A, b) * B
        levels[-1].B = B
        if A.symmetry == "nonsymmetric":
            BH = relaxation_as_linear_operator((fn, kwargs), AH, b) * BH
            levels[-1].BH = BH

    ##
    # Compute the tentative prolongator, T, which is a tentative interpolation
    # matrix from the coarse-grid to the fine-grid.  T exactly interpolates
    # B_fine[:,0:blocksize(A)] = T B_coarse[:,0:blocksize(A)].
    T, dummy = fit_candidates(AggOp, B[:, 0:blocksize(A)])
    del dummy
    if A.symmetry == "nonsymmetric":
        TH, dummyH = fit_candidates(AggOp, BH[:, 0:blocksize(A)])
        del dummyH

    ##
    # Create necessary root node matrices
    Cpt_params = (True, get_Cpt_params(A, Cnodes, AggOp, T))
    T = scale_T(T, Cpt_params[1]['P_I'], Cpt_params[1]['I_F'])
    if A.symmetry == "nonsymmetric":
        TH = scale_T(TH, Cpt_params[1]['P_I'], Cpt_params[1]['I_F'])

    ##
    # Set coarse grid near nullspace modes as injected fine grid near
    # null-space modes
    B = Cpt_params[1]['P_I'].T * levels[-1].B
    if A.symmetry == "nonsymmetric":
        BH = Cpt_params[1]['P_I'].T * levels[-1].BH

    ##
    # Smooth the tentative prolongator, so that it's accuracy is greatly improved
    # for algebraically smooth error.
    fn, kwargs = unpack_arg(smooth[len(levels) - 1])
    if fn == 'energy':
        P = energy_prolongation_smoother(A,
                                         T,
                                         C,
                                         B,
                                         levels[-1].B,
                                         Cpt_params=Cpt_params,
                                         **kwargs)
    elif fn is None:
        P = T
    else:
        raise ValueError('unrecognized prolongation smoother method %s' %
                         str(fn))

    ##
    # Compute the restriction matrix R, which interpolates from the fine-grid
    # to the coarse-grid.  If A is nonsymmetric, then R must be constructed
    # based on A.H.  Otherwise R = P.H or P.T.
    symmetry = A.symmetry
    if symmetry == 'hermitian':
        R = P.H
    elif symmetry == 'symmetric':
        R = P.T
    elif symmetry == 'nonsymmetric':
        fn, kwargs = unpack_arg(smooth[len(levels) - 1])
        if fn == 'energy':
            R = energy_prolongation_smoother(AH,
                                             TH,
                                             C,
                                             BH,
                                             levels[-1].BH,
                                             Cpt_params=Cpt_params,
                                             **kwargs)
            R = R.H
        elif fn is None:
            R = T.H
        else:
            raise ValueError('unrecognized prolongation smoother method %s' %
                             str(fn))

    if keep:
        levels[-1].C = C  # strength of connection matrix
        levels[-1].AggOp = AggOp  # aggregation operator
        levels[-1].T = T  # tentative prolongator
        levels[-1].Fpts = Cpt_params[1]['Fpts']  # Fpts
        levels[-1].P_I = Cpt_params[1]['P_I']  # Injection operator
        levels[-1].I_F = Cpt_params[1]['I_F']  # Identity on F-pts
        levels[-1].I_C = Cpt_params[1]['I_C']  # Identity on C-pts

    levels[-1].P = P  # smoothed prolongator
    levels[-1].R = R  # restriction operator
    levels[-1].Cpts = Cpt_params[1]['Cpts']  # Cpts (i.e., rootnodes)

    levels.append(multilevel_solver.level())
    A = R * A * P  # Galerkin operator
    A.symmetry = symmetry
    levels[-1].A = A
    levels[-1].B = B  # right near nullspace candidates

    if A.symmetry == "nonsymmetric":
        levels[-1].BH = BH  # left near nullspace candidates
Esempio n. 4
0
def extend_hierarchy(levels, strength, aggregate, smooth, improve_candidates, 
                     diagonal_dominance=False, keep=True):
    """Service routine to implement the strength of connection, aggregation,
    tentative prolongation construction, and prolongation smoothing.  Called by
    smoothed_aggregation_solver.
    """

    def unpack_arg(v):
        if isinstance(v,tuple):
            return v[0],v[1]
        else:
            return v,{}

    A = levels[-1].A
    B = levels[-1].B
    if A.symmetry == "nonsymmetric":
        AH = A.H.asformat(A.format)
        BH = levels[-1].BH
 
    ##
    # Compute the strength-of-connection matrix C, where larger 
    # C[i,j] denote stronger couplings between i and j.
    fn, kwargs = unpack_arg(strength[len(levels)-1])
    if fn == 'symmetric':
        C = symmetric_strength_of_connection(A, **kwargs)
    elif fn == 'classical':
        C = classical_strength_of_connection(A, **kwargs)
    elif fn == 'distance':
        C = distance_strength_of_connection(A, **kwargs)
    elif (fn == 'ode') or (fn == 'evolution'):
        if kwargs.has_key('B'):
            C = evolution_strength_of_connection(A, **kwargs)
        else:
            C = evolution_strength_of_connection(A, B, **kwargs)
    elif fn == 'energy_based':
        C = energy_based_strength_of_connection(A, **kwargs)
    elif fn == 'predefined':
        C = kwargs['C'].tocsr()
    elif fn == 'algebraic_distance':
        C = algebraic_distance(A, **kwargs)
    elif fn is None:
        C = A.tocsr()
    else:
        raise ValueError('unrecognized strength of connection method: %s' %
                         str(fn))
    
    ##
    # Avoid coarsening diagonally dominant rows
    flag,kwargs = unpack_arg( diagonal_dominance )
    if flag:
        C = eliminate_diag_dom_nodes(A, C, **kwargs)

    ##
    # Compute the aggregation matrix AggOp (i.e., the nodal coarsening of A).
    # AggOp is a boolean matrix, where the sparsity pattern for the k-th column
    # denotes the fine-grid nodes agglomerated into k-th coarse-grid node.
    fn, kwargs = unpack_arg(aggregate[len(levels)-1])
    if fn == 'standard':
        AggOp,Cnodes = standard_aggregation(C, **kwargs)
    elif fn == 'naive':
        AggOp,Cnodes = naive_aggregation(C, **kwargs)
    elif fn == 'lloyd':
        AggOp,Cnodes = lloyd_aggregation(C, **kwargs)
    elif fn == 'predefined':
        AggOp = kwargs['AggOp'].tocsr()
        Cnodes = kwargs['Cnodes']
    else:
        raise ValueError('unrecognized aggregation method %s' % str(fn))

    ##
    # Improve near nullspace candidates by relaxing on A B = 0
    fn, kwargs = unpack_arg( improve_candidates[len(levels)-1] )
    if fn is not None: 
        b = numpy.zeros((A.shape[0],1), dtype=A.dtype)
        B = relaxation_as_linear_operator((fn, kwargs), A, b) * B
        levels[-1].B = B
        if A.symmetry == "nonsymmetric":
            BH = relaxation_as_linear_operator((fn, kwargs), AH, b) * BH 
            levels[-1].BH = BH

    ##
    # Compute the tentative prolongator, T, which is a tentative interpolation
    # matrix from the coarse-grid to the fine-grid.  T exactly interpolates
    # B_fine[:,0:blocksize(A)] = T B_coarse[:,0:blocksize(A)].
    T,dummy = fit_candidates(AggOp,B[:,0:blocksize(A)])
    del dummy
    if A.symmetry == "nonsymmetric":
        TH,dummyH = fit_candidates(AggOp,BH[:,0:blocksize(A)])
        del dummyH

    ##
    # Create necessary root node matrices
    Cpt_params = (True, get_Cpt_params(A, Cnodes, AggOp, T))
    T = scale_T(T, Cpt_params[1]['P_I'], Cpt_params[1]['I_F'])
    if A.symmetry == "nonsymmetric":
        TH = scale_T(TH, Cpt_params[1]['P_I'], Cpt_params[1]['I_F'])
        
    ##
    # Set coarse grid near nullspace modes as injected fine grid near
    # null-space modes
    B = Cpt_params[1]['P_I'].T*levels[-1].B
    if A.symmetry == "nonsymmetric":
        BH = Cpt_params[1]['P_I'].T*levels[-1].BH


    ##
    # Smooth the tentative prolongator, so that it's accuracy is greatly improved
    # for algebraically smooth error.
    fn, kwargs = unpack_arg(smooth[len(levels)-1])
    if fn == 'energy':
        P = energy_prolongation_smoother(A, T, C, B, levels[-1].B, Cpt_params=Cpt_params, **kwargs)
    elif fn is None:
        P = T
    else:
        raise ValueError('unrecognized prolongation smoother method %s' % str(fn))

    ##
    # Compute the restriction matrix R, which interpolates from the fine-grid
    # to the coarse-grid.  If A is nonsymmetric, then R must be constructed
    # based on A.H.  Otherwise R = P.H or P.T.
    symmetry = A.symmetry
    if symmetry == 'hermitian':
        R = P.H
    elif symmetry == 'symmetric':
        R = P.T
    elif symmetry == 'nonsymmetric':
        fn, kwargs = unpack_arg(smooth[len(levels)-1])
        if fn == 'energy':
            R = energy_prolongation_smoother(AH, TH, C, BH, levels[-1].BH, Cpt_params=Cpt_params, **kwargs)
            R = R.H
        elif fn is None:
            R = T.H
        else:
            raise ValueError('unrecognized prolongation smoother method %s' % str(fn))

    if keep:
        levels[-1].C     = C                      # strength of connection matrix
        levels[-1].AggOp = AggOp                  # aggregation operator
        levels[-1].T     = T                      # tentative prolongator
        levels[-1].Fpts  = Cpt_params[1]['Fpts']  # Fpts    
        levels[-1].P_I   = Cpt_params[1]['P_I']   # Injection operator 
        levels[-1].I_F   = Cpt_params[1]['I_F']   # Identity on F-pts
        levels[-1].I_C   = Cpt_params[1]['I_C']   # Identity on C-pts

    levels[-1].P     = P                          # smoothed prolongator
    levels[-1].R     = R                          # restriction operator 
    levels[-1].Cpts  = Cpt_params[1]['Cpts']      # Cpts (i.e., rootnodes) 

    levels.append( multilevel_solver.level() )
    A = R * A * P                                 # Galerkin operator
    A.symmetry = symmetry
    levels[-1].A = A
    levels[-1].B = B                              # right near nullspace candidates

    if A.symmetry == "nonsymmetric":
        levels[-1].BH = BH                        # left near nullspace candidates
Esempio n. 5
0
def extend_hierarchy(levels, strength, aggregate, smooth, improve_candidates,
                     diagonal_dominance=False, keep=True, test_ind=0):
    """Service routine to implement the strength of connection, aggregation,
    tentative prolongation construction, and prolongation smoothing.  Called by
    smoothed_aggregation_solver.
    """

    def unpack_arg(v):
        if isinstance(v, tuple):
            return v[0], v[1]
        else:
            return v, {}

    A = levels[-1].A
    B = levels[-1].B
    if A.symmetry == "nonsymmetric":
        AH = A.H.asformat(A.format)
        BH = levels[-1].BH

    # Improve near nullspace candidates by relaxing on A B = 0
    fn, kwargs = unpack_arg(improve_candidates[len(levels)-1])
    if fn is not None:
        b = np.zeros((A.shape[0], 1), dtype=A.dtype)
        B = relaxation_as_linear_operator((fn, kwargs), A, b) * B
        levels[-1].B = B
        if A.symmetry == "nonsymmetric":
            BH = relaxation_as_linear_operator((fn, kwargs), AH, b) * BH
            levels[-1].BH = BH

    # Compute the strength-of-connection matrix C, where larger
    # C[i, j] denote stronger couplings between i and j.
    fn, kwargs = unpack_arg(strength[len(levels)-1])
    if fn == 'symmetric':
        C = symmetric_strength_of_connection(A, **kwargs)
    elif fn == 'classical':
        C = classical_strength_of_connection(A, **kwargs)
    elif fn == 'distance':
        C = distance_strength_of_connection(A, **kwargs)
    elif (fn == 'ode') or (fn == 'evolution'):
        if 'B' in kwargs:
            C = evolution_strength_of_connection(A, **kwargs)
        else:
            C = evolution_strength_of_connection(A, B, **kwargs)
    elif fn == 'energy_based':
        C = energy_based_strength_of_connection(A, **kwargs)
    elif fn == 'predefined':
        C = kwargs['C'].tocsr()
    elif fn == 'algebraic_distance':
        C = algebraic_distance(A, **kwargs)
    elif fn is None:
        C = A.tocsr()
    else:
        raise ValueError('unrecognized strength of connection method: %s' %
                         str(fn))

    # Avoid coarsening diagonally dominant rows
    flag, kwargs = unpack_arg(diagonal_dominance)
    if flag:
        C = eliminate_diag_dom_nodes(A, C, **kwargs)

    # Compute the aggregation matrix AggOp (i.e., the nodal coarsening of A).
    # AggOp is a boolean matrix, where the sparsity pattern for the k-th column
    # denotes the fine-grid nodes agglomerated into k-th coarse-grid node.
    fn, kwargs = unpack_arg(aggregate[len(levels)-1])
    if fn == 'standard':
        AggOp, Cnodes = standard_aggregation(C, **kwargs)
    elif fn == 'naive':
        AggOp, Cnodes = naive_aggregation(C, **kwargs)
    elif fn == 'lloyd':
        AggOp, Cnodes = lloyd_aggregation(C, **kwargs)
    elif fn == 'pairwise':
        AggOp, Cnodes = pairwise_aggregation(A, B, **kwargs)
    elif fn == 'predefined':
        AggOp = kwargs['AggOp'].tocsr()
        Cnodes = kwargs['Cnodes']
    else:
        raise ValueError('unrecognized aggregation method %s' % str(fn))

# ----------------------------------------------------------------------------- #
# ------------------- New ideal interpolation constructed --------------------  #
# ----------------------------------------------------------------------------- #

    # pdb.set_trace()

    # splitting = CR(A)
    # Cpts = [i for i in range(0,AggOp.shape[0]) if splitting[i]==1]

    # Compute prolongation operator.
    if test_ind==0:
        T = new_ideal_interpolation(A=A, AggOp=AggOp, Cnodes=Cnodes, B=B[:, 0:blocksize(A)], SOC=C)
    else: 
        T = py_ideal_interpolation(A=A, AggOp=AggOp, Cnodes=Cnodes, B=B[:, 0:blocksize(A)], SOC=C)

    print "\nSize of sparsity pattern - ", T.nnz

    # Smooth the tentative prolongator, so that it's accuracy is greatly
    # improved for algebraically smooth error.
    # fn, kwargs = unpack_arg(smooth[len(levels)-1])
    # if fn == 'jacobi':
    #     P = jacobi_prolongation_smoother(A, T, C, B, **kwargs)
    # elif fn == 'richardson':
    #     P = richardson_prolongation_smoother(A, T, **kwargs)
    # elif fn == 'energy':
    #     P = energy_prolongation_smoother(A, T, C, B, None, (False, {}),
    #                                      **kwargs)
    # elif fn is None:
    #     P = T
    # else:
    #     raise ValueError('unrecognized prolongation smoother method %s' %
    #                      str(fn))
    P = T
  
# ----------------------------------------------------------------------------- #
# ----------------------------------------------------------------------------- #

    # Compute the restriction matrix R, which interpolates from the fine-grid
    # to the coarse-grid.  If A is nonsymmetric, then R must be constructed
    # based on A.H.  Otherwise R = P.H or P.T.
    symmetry = A.symmetry
    if symmetry == 'hermitian':
        # symmetrically scale out the diagonal, include scaling in P, R
        A = P.H * A * P
        [dum, Dinv, dum] = symmetric_rescaling(A,copy=False)
        P = bsr_matrix(P * diags(Dinv,offsets=0,format='csr'), blocksize=A.blocksize)
        del dum
        R = P.H
    elif symmetry == 'symmetric':
        # symmetrically scale out the diagonal, include scaling in P, R
        A = P.T * A * P
        [dum, Dinv, dum] = symmetric_rescaling(A,copy=False)
        P = bsr_matrix(P * diags(Dinv,offsets=0,format='csr'), blocksize=A.blocksize)
        del dum
        R = P.T
    elif symmetry == 'nonsymmetric':
        raise TypeError('New ideal interpolation not implemented for non-symmetric matrix.')

    if keep:
        levels[-1].C = C                        # strength of connection matrix
        levels[-1].AggOp = AggOp                # aggregation operator
        levels[-1].Fpts = [i for i in range(0,AggOp.shape[0]) if i not in Cnodes]

    levels[-1].P = P                            # smoothed prolongator
    levels[-1].R = R                            # restriction operator
    levels[-1].Cpts = Cnodes                    # Cpts (i.e., rootnodes)

    levels.append(multilevel_solver.level())

    A.symmetry = symmetry
    levels[-1].A = A
    levels[-1].B = R*B                     # right near nullspace candidates

    test = A.tocsr()
    print "\nSize of coarse operator - ", test.nnz

    if A.symmetry == "nonsymmetric":
        levels[-1].BH = BH                      # left near nullspace candidates