Example #1
0
def _assemble(f,
              tensor=None,
              bcs=None,
              form_compiler_parameters=None,
              inverse=False,
              mat_type=None,
              sub_mat_type=None,
              appctx={},
              options_prefix=None,
              collect_loops=False,
              allocate_only=False):
    """Assemble the form or Slate expression f and return a Firedrake object
    representing the result. This will be a :class:`float` for 0-forms/rank-0
    Slate tensors, a :class:`.Function` for 1-forms/rank-1 Slate tensors and
    a :class:`.Matrix` for 2-forms/rank-2 Slate tensors.

    :arg bcs: A tuple of :class`.DirichletBC`\s to be applied.
    :arg tensor: An existing tensor object into which the form should be
        assembled. If this is not supplied, a new tensor will be created for
        the purpose.
    :arg form_compiler_parameters: (optional) dict of parameters to pass to
        the form compiler.
    :arg inverse: (optional) if f is a 2-form, then assemble the inverse
         of the local matrices.
    :arg mat_type: (optional) type for assembled matrices, one of
        "nest", "aij", "baij", or "matfree".
    :arg sub_mat_type: (optional) type for assembled sub matrices
        inside a "nest" matrix.  One of "aij" or "baij".
    :arg appctx: Additional information to hang on the assembled
         matrix if an implicit matrix is requested (mat_type "matfree").
    :arg options_prefix: An options prefix for the PETSc matrix
        (ignored if not assembling a bilinear form).
    """
    if mat_type is None:
        mat_type = parameters.parameters["default_matrix_type"]
    if mat_type not in ["matfree", "aij", "baij", "nest"]:
        raise ValueError("Unrecognised matrix type, '%s'" % mat_type)
    if sub_mat_type is None:
        sub_mat_type = parameters.parameters["default_sub_matrix_type"]
    if sub_mat_type not in ["aij", "baij"]:
        raise ValueError("Invalid submatrix type, '%s' (not 'aij' or 'baij')",
                         sub_mat_type)

    if form_compiler_parameters:
        form_compiler_parameters = form_compiler_parameters.copy()
    else:
        form_compiler_parameters = {}
    form_compiler_parameters["assemble_inverse"] = inverse

    topology = f.ufl_domains()[0].topology
    for m in f.ufl_domains():
        # Ensure mesh is "initialised" (could have got here without
        # building a functionspace (e.g. if integrating a constant)).
        m.init()
        if m.topology != topology:
            raise NotImplementedError(
                "All integration domains must share a mesh topology.")

    for o in chain(f.arguments(), f.coefficients()):
        domain = o.ufl_domain()
        if domain is not None and domain.topology != topology:
            raise NotImplementedError(
                "Assembly with multiple meshes not supported.")

    if isinstance(f, slate.TensorBase):
        kernels = slac.compile_expression(
            f, tsfc_parameters=form_compiler_parameters)
        integral_types = [kernel.kinfo.integral_type for kernel in kernels]
    else:
        kernels = tsfc_interface.compile_form(
            f, "form", parameters=form_compiler_parameters, inverse=inverse)
        integral_types = [
            integral.integral_type() for integral in f.integrals()
        ]

    rank = len(f.arguments())

    is_mat = rank == 2
    is_vec = rank == 1

    if any((coeff.function_space()
            and coeff.function_space().component is not None)
           for coeff in f.coefficients()):
        raise NotImplementedError(
            "Integration of subscripted VFS not yet implemented")

    if inverse and rank != 2:
        raise ValueError("Can only assemble the inverse of a 2-form")

    zero_tensor = lambda: None

    if is_mat:
        matfree = mat_type == "matfree"
        nest = mat_type == "nest"
        if nest:
            baij = sub_mat_type == "baij"
        else:
            baij = mat_type == "baij"
        if matfree:  # intercept matrix-free matrices here
            if inverse:
                raise NotImplementedError(
                    "Inverse not implemented with matfree")
            if collect_loops:
                raise NotImplementedError("Can't collect loops with matfree")
            if tensor is None:
                return matrix.ImplicitMatrix(
                    f,
                    bcs,
                    fc_params=form_compiler_parameters,
                    appctx=appctx,
                    options_prefix=options_prefix)
            if not isinstance(tensor, matrix.ImplicitMatrix):
                raise ValueError("Expecting implicit matrix with matfree")
            tensor.assemble()
            return tensor
        test, trial = f.arguments()

        map_pairs = []
        cell_domains = []
        exterior_facet_domains = []
        interior_facet_domains = []
        if tensor is None:
            # For horizontal facets of extruded meshes, the corresponding domain
            # in the base mesh is the cell domain. Hence all the maps used for top
            # bottom and interior horizontal facets will use the cell to dofs map
            # coming from the base mesh as a starting point for the actual dynamic map
            # computation.
            for integral_type in integral_types:
                if integral_type == "cell":
                    cell_domains.append(op2.ALL)
                elif integral_type == "exterior_facet":
                    exterior_facet_domains.append(op2.ALL)
                elif integral_type == "interior_facet":
                    interior_facet_domains.append(op2.ALL)
                elif integral_type == "exterior_facet_bottom":
                    cell_domains.append(op2.ON_BOTTOM)
                elif integral_type == "exterior_facet_top":
                    cell_domains.append(op2.ON_TOP)
                elif integral_type == "exterior_facet_vert":
                    exterior_facet_domains.append(op2.ALL)
                elif integral_type == "interior_facet_horiz":
                    cell_domains.append(op2.ON_INTERIOR_FACETS)
                elif integral_type == "interior_facet_vert":
                    interior_facet_domains.append(op2.ALL)
                else:
                    raise ValueError('Unknown integral type "%s"' %
                                     integral_type)

            # To avoid an extra check for extruded domains, the maps that are being passed in
            # are DecoratedMaps. For the non-extruded case the DecoratedMaps don't restrict the
            # space over which we iterate as the domains are dropped at Sparsity construction
            # time. In the extruded case the cell domains are used to identify the regions of the
            # mesh which require allocation in the sparsity.
            if cell_domains:
                map_pairs.append(
                    (op2.DecoratedMap(test.cell_node_map(), cell_domains),
                     op2.DecoratedMap(trial.cell_node_map(), cell_domains)))
            if exterior_facet_domains:
                map_pairs.append(
                    (op2.DecoratedMap(test.exterior_facet_node_map(),
                                      exterior_facet_domains),
                     op2.DecoratedMap(trial.exterior_facet_node_map(),
                                      exterior_facet_domains)))
            if interior_facet_domains:
                map_pairs.append(
                    (op2.DecoratedMap(test.interior_facet_node_map(),
                                      interior_facet_domains),
                     op2.DecoratedMap(trial.interior_facet_node_map(),
                                      interior_facet_domains)))

            map_pairs = tuple(map_pairs)
            # Construct OP2 Mat to assemble into
            fs_names = (test.function_space().name,
                        trial.function_space().name)

            try:
                sparsity = op2.Sparsity((test.function_space().dof_dset,
                                         trial.function_space().dof_dset),
                                        map_pairs,
                                        "%s_%s_sparsity" % fs_names,
                                        nest=nest,
                                        block_sparse=baij)
            except SparsityFormatError:
                raise ValueError(
                    "Monolithic matrix assembly is not supported for systems with R-space blocks."
                )

            result_matrix = matrix.Matrix(f,
                                          bcs,
                                          mat_type,
                                          sparsity,
                                          numpy.float64,
                                          "%s_%s_matrix" % fs_names,
                                          options_prefix=options_prefix)
            tensor = result_matrix._M
        else:
            if isinstance(tensor, matrix.ImplicitMatrix):
                raise ValueError("Expecting matfree with implicit matrix")

            result_matrix = tensor
            # Replace any bcs on the tensor we passed in
            result_matrix.bcs = bcs
            tensor = tensor._M
            zero_tensor = tensor.zero

        if result_matrix.block_shape != (1, 1) and mat_type == "baij":
            raise ValueError(
                "BAIJ matrix type makes no sense for mixed spaces, use 'aij'")

        def mat(testmap, trialmap, i, j):
            m = testmap(test.function_space()[i])
            n = trialmap(trial.function_space()[j])
            maps = (m[op2.i[0]] if m else None,
                    n[op2.i[1 if m else 0]] if n else None)
            return tensor[i, j](op2.INC, maps)

        result = lambda: result_matrix
        if allocate_only:
            result_matrix._assembly_callback = None
            return result_matrix
    elif is_vec:
        test = f.arguments()[0]
        if tensor is None:
            result_function = function.Function(test.function_space())
            tensor = result_function.dat
        else:
            result_function = tensor
            tensor = result_function.dat
            zero_tensor = tensor.zero

        def vec(testmap, i):
            _testmap = testmap(test.function_space()[i])
            return tensor[i](op2.INC, _testmap[op2.i[0]] if _testmap else None)

        result = lambda: result_function
    else:
        # 0-forms are always scalar
        if tensor is None:
            tensor = op2.Global(1, [0.0])
        else:
            raise ValueError("Can't assemble 0-form into existing tensor")
        result = lambda: tensor.data[0]

    coefficients = f.coefficients()
    domains = f.ufl_domains()

    # These will be used to correctly interpret the "otherwise"
    # subdomain
    all_integer_subdomain_ids = defaultdict(list)
    for k in kernels:
        if k.kinfo.subdomain_id != "otherwise":
            all_integer_subdomain_ids[k.kinfo.integral_type].append(
                k.kinfo.subdomain_id)
    for k, v in all_integer_subdomain_ids.items():
        all_integer_subdomain_ids[k] = tuple(sorted(v))

    # Since applying boundary conditions to a matrix changes the
    # initial assembly, to support:
    #     A = assemble(a)
    #     bc.apply(A)
    #     solve(A, ...)
    # we need to defer actually assembling the matrix until just
    # before we need it (when we know if there are any bcs to be
    # applied).  To do so, we build a closure that carries out the
    # assembly and stash that on the Matrix object.  When we hit a
    # solve, we funcall the closure with any bcs the Matrix now has to
    # assemble it.

    # In collecting loops mode, we collect the loops, and assume the
    # boundary conditions provided are the ones we want.  It therefore
    # is only used inside residual and jacobian assembly.
    loops = []

    def thunk(bcs):
        if collect_loops:
            loops.append(zero_tensor)
        else:
            zero_tensor()
        for indices, kinfo in kernels:
            kernel = kinfo.kernel
            integral_type = kinfo.integral_type
            domain_number = kinfo.domain_number
            subdomain_id = kinfo.subdomain_id
            coeff_map = kinfo.coefficient_map
            pass_layer_arg = kinfo.pass_layer_arg
            needs_orientations = kinfo.oriented
            needs_cell_facets = kinfo.needs_cell_facets
            needs_cell_sizes = kinfo.needs_cell_sizes

            m = domains[domain_number]
            subdomain_data = f.subdomain_data()[m]
            # Find argument space indices
            if is_mat:
                i, j = indices
            elif is_vec:
                i, = indices
            else:
                assert len(indices) == 0

            sdata = subdomain_data.get(integral_type, None)
            if integral_type != 'cell' and sdata is not None:
                raise NotImplementedError(
                    "subdomain_data only supported with cell integrals.")

            # Extract block from tensor and test/trial spaces
            # FIXME Ugly variable renaming required because functions are not
            # lexical closures in Python and we're writing to these variables
            if is_mat and result_matrix.block_shape > (1, 1):
                tsbc = []
                trbc = []
                # Unwind ComponentFunctionSpace to check for matching BCs
                for bc in bcs:
                    fs = bc.function_space()
                    if fs.component is not None:
                        fs = fs.parent
                    if fs.index == i:
                        tsbc.append(bc)
                    if fs.index == j:
                        trbc.append(bc)
            elif is_mat:
                tsbc, trbc = bcs, bcs

            # Now build arguments for the par_loop
            kwargs = {}
            # Some integrals require non-coefficient arguments at the
            # end (facet number information).
            extra_args = []
            # Decoration for applying to matrix maps in extruded case
            decoration = None
            itspace = m.measure_set(integral_type, subdomain_id,
                                    all_integer_subdomain_ids)
            if integral_type == "cell":
                itspace = sdata or itspace

                if subdomain_id not in ["otherwise", "everywhere"] and \
                   sdata is not None:
                    raise ValueError(
                        "Cannot use subdomain data and subdomain_id")

                def get_map(x, bcs=None, decoration=None):
                    return x.cell_node_map(bcs)

            elif integral_type in ("exterior_facet", "exterior_facet_vert"):
                extra_args.append(m.exterior_facets.local_facet_dat(op2.READ))

                def get_map(x, bcs=None, decoration=None):
                    return x.exterior_facet_node_map(bcs)

            elif integral_type in ("exterior_facet_top",
                                   "exterior_facet_bottom"):
                # In the case of extruded meshes with horizontal facet integrals, two
                # parallel loops will (potentially) get created and called based on the
                # domain id: interior horizontal, bottom or top.
                decoration = {
                    "exterior_facet_top": op2.ON_TOP,
                    "exterior_facet_bottom": op2.ON_BOTTOM
                }[integral_type]
                kwargs["iterate"] = decoration

                def get_map(x, bcs=None, decoration=None):
                    map_ = x.cell_node_map(bcs)
                    if decoration is not None:
                        return op2.DecoratedMap(map_, decoration)
                    return map_

            elif integral_type in ("interior_facet", "interior_facet_vert"):
                extra_args.append(m.interior_facets.local_facet_dat(op2.READ))

                def get_map(x, bcs=None, decoration=None):
                    return x.interior_facet_node_map(bcs)

            elif integral_type == "interior_facet_horiz":
                decoration = op2.ON_INTERIOR_FACETS
                kwargs["iterate"] = decoration

                def get_map(x, bcs=None, decoration=None):
                    map_ = x.cell_node_map(bcs)
                    if decoration is not None:
                        return op2.DecoratedMap(map_, decoration)
                    return map_

            else:
                raise ValueError("Unknown integral type '%s'" % integral_type)

            # Output argument
            if is_mat:
                tensor_arg = mat(lambda s: get_map(s, tsbc, decoration),
                                 lambda s: get_map(s, trbc, decoration), i, j)
            elif is_vec:
                tensor_arg = vec(lambda s: get_map(s), i)
            else:
                tensor_arg = tensor(op2.INC)

            coords = m.coordinates
            args = [
                kernel, itspace, tensor_arg,
                coords.dat(op2.READ,
                           get_map(coords)[op2.i[0]])
            ]
            if needs_orientations:
                o = m.cell_orientations()
                args.append(o.dat(op2.READ, get_map(o)[op2.i[0]]))
            if needs_cell_sizes:
                o = m.cell_sizes
                args.append(o.dat(op2.READ, get_map(o)[op2.i[0]]))
            for n in coeff_map:
                c = coefficients[n]
                for c_ in c.split():
                    m_ = get_map(c_)
                    args.append(c_.dat(op2.READ, m_ and m_[op2.i[0]]))
            if needs_cell_facets:
                assert integral_type == "cell"
                extra_args.append(m.cell_to_facets(op2.READ))

            args.extend(extra_args)
            kwargs["pass_layer_arg"] = pass_layer_arg

            try:
                with collecting_loops(collect_loops):
                    loops.append(op2.par_loop(*args, **kwargs))
            except MapValueError:
                raise RuntimeError(
                    "Integral measure does not match measure of all coefficients/arguments"
                )

        # Must apply bcs outside loop over kernels because we may wish
        # to apply bcs to a block which is otherwise zero, and
        # therefore does not have an associated kernel.
        if bcs is not None and is_mat:
            for bc in bcs:
                fs = bc.function_space()
                # Evaluate this outwith a "collecting_loops" block,
                # since creation of the bc nodes actually can create a
                # par_loop.
                nodes = bc.nodes
                if len(fs) > 1:
                    raise RuntimeError(
                        """Cannot apply boundary conditions to full mixed space. Did you forget to index it?"""
                    )
                shape = result_matrix.block_shape
                with collecting_loops(collect_loops):
                    for i in range(shape[0]):
                        for j in range(shape[1]):
                            # Set diagonal entries on bc nodes to 1 if the current
                            # block is on the matrix diagonal and its index matches the
                            # index of the function space the bc is defined on.
                            if i != j:
                                continue
                            if fs.component is None and fs.index is not None:
                                # Mixed, index (no ComponentFunctionSpace)
                                if fs.index == i:
                                    loops.append(tensor[
                                        i,
                                        j].set_local_diagonal_entries(nodes))
                            elif fs.component is not None:
                                # ComponentFunctionSpace, check parent index
                                if fs.parent.index is not None:
                                    # Mixed, index doesn't match
                                    if fs.parent.index != i:
                                        continue
                                # Index matches
                                loops.append(
                                    tensor[i, j].set_local_diagonal_entries(
                                        nodes, idx=fs.component))
                            elif fs.index is None:
                                loops.append(tensor[
                                    i, j].set_local_diagonal_entries(nodes))
                            else:
                                raise RuntimeError("Unhandled BC case")
        if bcs is not None and is_vec:
            if len(bcs) > 0 and collect_loops:
                raise NotImplementedError(
                    "Loop collection not handled in this case")
            for bc in bcs:
                bc.apply(result_function)
        if is_mat:
            # Queue up matrix assembly (after we've done all the other operations)
            loops.append(tensor.assemble())
        return result()

    if collect_loops:
        thunk(bcs)
        return loops
    if is_mat:
        result_matrix._assembly_callback = thunk
        return result()
    else:
        return thunk(bcs)
Example #2
0
def get_matrix(expr,
               mat_type,
               sub_mat_type,
               *,
               bcs=None,
               options_prefix=None,
               tensor=None,
               appctx=None,
               form_compiler_parameters=None):
    """Get a matrix for the assembly of expr.

    :arg mat_type, sub_mat_type: See :func:`get_mat_type`.
    :arg bcs: Boundary conditions.
    :arg options_prefix: Optional PETSc options prefix.
    :arg tensor: An optional already allocated matrix for this expr.
    :arg appctx: User application data.
    :arg form_compiler_parameters: Any parameters for the form compiler.

    :raises ValueError: In case of problems.
    :returns: a 3-tuple ``(tensor, zeros, callable)``. zeros is a
       (possibly empty) iterable of zero-argument functions to zero the returned
       tensor, callable is a function of zero arguments that returns
       the tensor.
    """
    mat_type, sub_mat_type = get_mat_type(mat_type, sub_mat_type,
                                          expr.arguments())
    matfree = mat_type == "matfree"
    arguments = expr.arguments()
    if bcs is None:
        bcs = ()
    else:
        if any(isinstance(bc, EquationBC) for bc in bcs):
            raise TypeError(
                "EquationBC objects not expected here. "
                "Preprocess by extracting the appropriate form with bc.extract_form('Jp') or bc.extract_form('J')"
            )
    if tensor is not None and tensor.a.arguments() != arguments:
        raise ValueError(
            "Form's arguments do not match provided result tensor")
    if matfree:
        if tensor is None:
            tensor = matrix.ImplicitMatrix(expr,
                                           bcs,
                                           fc_params=form_compiler_parameters,
                                           appctx=appctx,
                                           options_prefix=options_prefix)
        elif not isinstance(tensor, matrix.ImplicitMatrix):
            raise ValueError("Expecting implicit matrix with matfree")
        else:
            pass
        return tensor, (), lambda: tensor

    if tensor is not None:
        return tensor, (tensor.M.zero, ), lambda: tensor

    integral_types = set(i.integral_type() for i in expr.integrals())
    for bc in bcs:
        integral_types.update(integral.integral_type()
                              for integral in bc.integrals())
    nest = mat_type == "nest"
    if nest:
        baij = sub_mat_type == "baij"
    else:
        baij = mat_type == "baij"

    if any(len(a.function_space()) > 1
           for a in arguments) and mat_type == "baij":
        raise ValueError(
            "BAIJ matrix type makes no sense for mixed spaces, use 'aij'")

    get_cell_map = operator.methodcaller("cell_node_map")
    get_extf_map = operator.methodcaller("exterior_facet_node_map")
    get_intf_map = operator.methodcaller("interior_facet_node_map")
    domains = OrderedDict(
        (k, set()) for k in (get_cell_map, get_extf_map, get_intf_map))
    mapping = {
        "cell": (get_cell_map, op2.ALL),
        "exterior_facet_bottom": (get_cell_map, op2.ON_BOTTOM),
        "exterior_facet_top": (get_cell_map, op2.ON_TOP),
        "interior_facet_horiz": (get_cell_map, op2.ON_INTERIOR_FACETS),
        "exterior_facet": (get_extf_map, op2.ALL),
        "exterior_facet_vert": (get_extf_map, op2.ALL),
        "interior_facet": (get_intf_map, op2.ALL),
        "interior_facet_vert": (get_intf_map, op2.ALL)
    }
    for integral_type in integral_types:
        try:
            get_map, region = mapping[integral_type]
        except KeyError:
            raise ValueError(f"Unknown integral type '{integral_type}'")
        domains[get_map].add(region)

    test, trial = arguments
    map_pairs, iteration_regions = zip(
        *(((get_map(test), get_map(trial)), tuple(sorted(regions)))
          for get_map, regions in domains.items() if regions))
    try:
        sparsity = op2.Sparsity(
            (test.function_space().dof_dset, trial.function_space().dof_dset),
            tuple(map_pairs),
            iteration_regions=tuple(iteration_regions),
            nest=nest,
            block_sparse=baij)
    except SparsityFormatError:
        raise ValueError(
            "Monolithic matrix assembly not supported for systems "
            "with R-space blocks")

    tensor = matrix.Matrix(expr,
                           bcs,
                           mat_type,
                           sparsity,
                           ScalarType,
                           options_prefix=options_prefix)
    return tensor, (), lambda: tensor
Example #3
0
def _make_matrix(expr, bcs, opts):
    """Make an empty matrix.

    :arg expr: The expression being assembled.
    :arg bcs: Iterable of boundary conditions.
    :arg opts: :class:`_AssemblyOpts` containing the assembly options.

    :returns: An empty :class:`.Matrix` or :class:`.ImplicitMatrix`.
    """
    matfree = opts.mat_type == "matfree"
    arguments = expr.arguments()
    if bcs is None:
        bcs = ()
    else:
        if any(isinstance(bc, EquationBC) for bc in bcs):
            raise TypeError(
                "EquationBC objects not expected here. "
                "Preprocess by extracting the appropriate form with bc.extract_form('Jp') or bc.extract_form('J')"
            )
    if matfree:
        return matrix.ImplicitMatrix(expr,
                                     bcs,
                                     fc_params=opts.fc_params,
                                     appctx=opts.appctx,
                                     options_prefix=opts.options_prefix)

    integral_types = set(i.integral_type() for i in expr.integrals())
    for bc in bcs:
        integral_types.update(integral.integral_type()
                              for integral in bc.integrals())
    nest = opts.mat_type == "nest"
    if nest:
        baij = opts.sub_mat_type == "baij"
    else:
        baij = opts.mat_type == "baij"

    if any(len(a.function_space()) > 1
           for a in arguments) and opts.mat_type == "baij":
        raise ValueError(
            "BAIJ matrix type makes no sense for mixed spaces, use 'aij'")

    get_cell_map = operator.methodcaller("cell_node_map")
    get_extf_map = operator.methodcaller("exterior_facet_node_map")
    get_intf_map = operator.methodcaller("interior_facet_node_map")
    domains = OrderedDict(
        (k, set()) for k in (get_cell_map, get_extf_map, get_intf_map))
    mapping = {
        "cell": (get_cell_map, op2.ALL),
        "exterior_facet_bottom": (get_cell_map, op2.ON_BOTTOM),
        "exterior_facet_top": (get_cell_map, op2.ON_TOP),
        "interior_facet_horiz": (get_cell_map, op2.ON_INTERIOR_FACETS),
        "exterior_facet": (get_extf_map, op2.ALL),
        "exterior_facet_vert": (get_extf_map, op2.ALL),
        "interior_facet": (get_intf_map, op2.ALL),
        "interior_facet_vert": (get_intf_map, op2.ALL)
    }
    for integral_type in integral_types:
        try:
            get_map, region = mapping[integral_type]
        except KeyError:
            raise ValueError(f"Unknown integral type '{integral_type}'")
        domains[get_map].add(region)

    test, trial = arguments
    map_pairs, iteration_regions = zip(
        *(((get_map(test), get_map(trial)), tuple(sorted(regions)))
          for get_map, regions in domains.items() if regions))
    try:
        sparsity = op2.Sparsity(
            (test.function_space().dof_dset, trial.function_space().dof_dset),
            tuple(map_pairs),
            iteration_regions=tuple(iteration_regions),
            nest=nest,
            block_sparse=baij)
    except SparsityFormatError:
        raise ValueError(
            "Monolithic matrix assembly not supported for systems "
            "with R-space blocks")

    return matrix.Matrix(expr,
                         bcs,
                         opts.mat_type,
                         sparsity,
                         ScalarType,
                         options_prefix=opts.options_prefix)
Example #4
0
def _assemble(f, tensor=None, bcs=None, form_compiler_parameters=None,
              inverse=False, nest=None):
    """Assemble the form f and return a Firedrake object representing the
    result. This will be a :class:`float` for 0-forms, a
    :class:`.Function` for 1-forms and a :class:`.Matrix` for 2-forms.

    :arg bcs: A tuple of :class`.DirichletBC`\s to be applied.
    :arg tensor: An existing tensor object into which the form should be
        assembled. If this is not supplied, a new tensor will be created for
        the purpose.
    :arg form_compiler_parameters: (optional) dict of parameters to pass to
        the form compiler.
    :arg inverse: (optional) if f is a 2-form, then assemble the inverse
         of the local matrices.
    :arg nest: (optional) flag indicating if matrices on mixed spaces
         should be built in blocks or monolithically.

    """

    if form_compiler_parameters:
        form_compiler_parameters = form_compiler_parameters.copy()
    else:
        form_compiler_parameters = {}
    form_compiler_parameters["assemble_inverse"] = inverse

    kernels = tsfc_interface.compile_form(f, "form", parameters=form_compiler_parameters,
                                          inverse=inverse)
    rank = len(f.arguments())

    is_mat = rank == 2
    is_vec = rank == 1

    if any((coeff.function_space() and coeff.function_space().component is not None)
           for coeff in f.coefficients()):
        raise NotImplementedError("Integration of subscripted VFS not yet implemented")

    if inverse and rank != 2:
        raise ValueError("Can only assemble the inverse of a 2-form")

    integrals = f.integrals()

    if nest is None:
        nest = parameters.parameters["matnest"]
    # Pass this through for assembly caching purposes
    form_compiler_parameters["matnest"] = nest

    zero_tensor = lambda: None

    if is_mat:
        test, trial = f.arguments()

        map_pairs = []
        cell_domains = []
        exterior_facet_domains = []
        interior_facet_domains = []
        if tensor is None:
            # For horizontal facets of extrded meshes, the corresponding domain
            # in the base mesh is the cell domain. Hence all the maps used for top
            # bottom and interior horizontal facets will use the cell to dofs map
            # coming from the base mesh as a starting point for the actual dynamic map
            # computation.
            for integral in integrals:
                integral_type = integral.integral_type()
                if integral_type == "cell":
                    cell_domains.append(op2.ALL)
                elif integral_type == "exterior_facet":
                    exterior_facet_domains.append(op2.ALL)
                elif integral_type == "interior_facet":
                    interior_facet_domains.append(op2.ALL)
                elif integral_type == "exterior_facet_bottom":
                    cell_domains.append(op2.ON_BOTTOM)
                elif integral_type == "exterior_facet_top":
                    cell_domains.append(op2.ON_TOP)
                elif integral_type == "exterior_facet_vert":
                    exterior_facet_domains.append(op2.ALL)
                elif integral_type == "interior_facet_horiz":
                    cell_domains.append(op2.ON_INTERIOR_FACETS)
                elif integral_type == "interior_facet_vert":
                    interior_facet_domains.append(op2.ALL)
                else:
                    raise ValueError('Unknown integral type "%s"' % integral_type)

            # To avoid an extra check for extruded domains, the maps that are being passed in
            # are DecoratedMaps. For the non-extruded case the DecoratedMaps don't restrict the
            # space over which we iterate as the domains are dropped at Sparsity construction
            # time. In the extruded case the cell domains are used to identify the regions of the
            # mesh which require allocation in the sparsity.
            if cell_domains:
                map_pairs.append((op2.DecoratedMap(test.cell_node_map(), cell_domains),
                                  op2.DecoratedMap(trial.cell_node_map(), cell_domains)))
            if exterior_facet_domains:
                map_pairs.append((op2.DecoratedMap(test.exterior_facet_node_map(), exterior_facet_domains),
                                  op2.DecoratedMap(trial.exterior_facet_node_map(), exterior_facet_domains)))
            if interior_facet_domains:
                map_pairs.append((op2.DecoratedMap(test.interior_facet_node_map(), interior_facet_domains),
                                  op2.DecoratedMap(trial.interior_facet_node_map(), interior_facet_domains)))

            map_pairs = tuple(map_pairs)
            # Construct OP2 Mat to assemble into
            fs_names = (test.function_space().name, trial.function_space().name)
            sparsity = op2.Sparsity((test.function_space().dof_dset,
                                     trial.function_space().dof_dset),
                                    map_pairs,
                                    "%s_%s_sparsity" % fs_names,
                                    nest=nest)
            result_matrix = matrix.Matrix(f, bcs, sparsity, numpy.float64,
                                          "%s_%s_matrix" % fs_names)
            tensor = result_matrix._M
        else:
            result_matrix = tensor
            # Replace any bcs on the tensor we passed in
            result_matrix.bcs = bcs
            tensor = tensor._M
            zero_tensor = lambda: tensor.zero()

        def mat(testmap, trialmap, i, j):
            return tensor[i, j](op2.INC,
                                (testmap(test.function_space()[i])[op2.i[0]],
                                 trialmap(trial.function_space()[j])[op2.i[1]]),
                                flatten=True)
        result = lambda: result_matrix
    elif is_vec:
        test = f.arguments()[0]
        if tensor is None:
            result_function = function.Function(test.function_space())
            tensor = result_function.dat
        else:
            result_function = tensor
            tensor = result_function.dat
            zero_tensor = lambda: tensor.zero()

        def vec(testmap, i):
            return tensor[i](op2.INC,
                             testmap(test.function_space()[i])[op2.i[0]],
                             flatten=True)
        result = lambda: result_function
    else:
        # 0-forms are always scalar
        if tensor is None:
            tensor = op2.Global(1, [0.0])
        result = lambda: tensor.data[0]

    subdomain_data = f.subdomain_data()
    coefficients = f.coefficients()
    domains = f.ufl_domains()
    if len(domains) != 1:
        raise NotImplementedError("Assembly of forms with more than one domain not supported")
    m = domains[0]
    # Ensure mesh is "initialised" (could have got here without
    # building a functionspace (e.g. if integrating a constant)).
    m.init()
    subdomain_data = subdomain_data[m]

    # Since applying boundary conditions to a matrix changes the
    # initial assembly, to support:
    #     A = assemble(a)
    #     bc.apply(A)
    #     solve(A, ...)
    # we need to defer actually assembling the matrix until just
    # before we need it (when we know if there are any bcs to be
    # applied).  To do so, we build a closure that carries out the
    # assembly and stash that on the Matrix object.  When we hit a
    # solve, we funcall the closure with any bcs the Matrix now has to
    # assemble it.
    def thunk(bcs):
        zero_tensor()
        for indices, (kernel, integral_type, needs_orientations, subdomain_id, coeff_map) in kernels:
            # Find argument space indices
            if is_mat:
                i, j = indices
            elif is_vec:
                i, = indices
            else:
                assert len(indices) == 0

            sdata = subdomain_data.get(integral_type, None)
            if integral_type != 'cell' and sdata is not None:
                raise NotImplementedError("subdomain_data only supported with cell integrals.")

            # Extract block from tensor and test/trial spaces
            # FIXME Ugly variable renaming required because functions are not
            # lexical closures in Python and we're writing to these variables
            if is_mat and tensor.sparsity.shape > (1, 1):
                tsbc = []
                trbc = []
                # Unwind ComponentFunctionSpace to check for matching BCs
                for bc in bcs:
                    fs = bc.function_space()
                    if fs.component is not None:
                        fs = fs.parent
                    if fs.index == i:
                        tsbc.append(bc)
                    if fs.index == j:
                        trbc.append(bc)
            elif is_mat:
                tsbc, trbc = bcs, bcs

            # Now build arguments for the par_loop
            kwargs = {}
            # Some integrals require non-coefficient arguments at the
            # end (facet number information).
            extra_args = []
            # Decoration for applying to matrix maps in extruded case
            decoration = None
            if integral_type == "cell":
                itspace = sdata or m.cell_set

                def get_map(x, bcs=None, decoration=None):
                    return x.cell_node_map(bcs)

            elif integral_type in ("exterior_facet", "exterior_facet_vert"):
                itspace = m.exterior_facets.measure_set(integral_type, subdomain_id)
                extra_args.append(m.exterior_facets.local_facet_dat(op2.READ))

                def get_map(x, bcs=None, decoration=None):
                    return x.exterior_facet_node_map(bcs)

            elif integral_type in ("exterior_facet_top", "exterior_facet_bottom"):
                # In the case of extruded meshes with horizontal facet integrals, two
                # parallel loops will (potentially) get created and called based on the
                # domain id: interior horizontal, bottom or top.
                index, itspace = m.exterior_facets.measure_set(integral_type, subdomain_id)
                decoration = index
                kwargs["iterate"] = index

                def get_map(x, bcs=None, decoration=None):
                    map_ = x.cell_node_map(bcs)
                    if decoration is not None:
                        return op2.DecoratedMap(map_, decoration)
                    return map_

            elif integral_type in ("interior_facet", "interior_facet_vert"):
                itspace = m.interior_facets.set
                extra_args.append(m.interior_facets.local_facet_dat(op2.READ))

                def get_map(x, bcs=None, decoration=None):
                    return x.interior_facet_node_map(bcs)

            elif integral_type == "interior_facet_horiz":
                itspace = m.interior_facets.measure_set(integral_type, subdomain_id)
                decoration = op2.ON_INTERIOR_FACETS
                kwargs["iterate"] = op2.ON_INTERIOR_FACETS

                def get_map(x, bcs=None, decoration=None):
                    map_ = x.cell_node_map(bcs)
                    if decoration is not None:
                        return op2.DecoratedMap(map_, decoration)
                    return map_

            else:
                raise ValueError("Unknown integral type '%s'" % integral_type)

            # Output argument
            if is_mat:
                tensor_arg = mat(lambda s: get_map(s, tsbc, decoration),
                                 lambda s: get_map(s, trbc, decoration),
                                 i, j)
            elif is_vec:
                tensor_arg = vec(lambda s: get_map(s), i)
            else:
                tensor_arg = tensor(op2.INC)

            coords = m.coordinates
            args = [kernel, itspace, tensor_arg,
                    coords.dat(op2.READ, get_map(coords), flatten=True)]
            if needs_orientations:
                o = m.cell_orientations()
                args.append(o.dat(op2.READ, get_map(o), flatten=True))
            for n in coeff_map:
                c = coefficients[n]
                args.append(c.dat(op2.READ, get_map(c), flatten=True))

            args.extend(extra_args)
            try:
                op2.par_loop(*args, **kwargs)
            except MapValueError:
                raise RuntimeError("Integral measure does not match measure of all coefficients/arguments")

        # Must apply bcs outside loop over kernels because we may wish
        # to apply bcs to a block which is otherwise zero, and
        # therefore does not have an associated kernel.
        if bcs is not None and is_mat:
            for bc in bcs:
                fs = bc.function_space()
                if len(fs) > 1:
                    raise RuntimeError("""Cannot apply boundary conditions to full mixed space. Did you forget to index it?""")
                shape = tensor.sparsity.shape
                for i in range(shape[0]):
                    for j in range(shape[1]):
                        # Set diagonal entries on bc nodes to 1 if the current
                        # block is on the matrix diagonal and its index matches the
                        # index of the function space the bc is defined on.
                        if i != j:
                            continue
                        if fs.component is None and fs.index is not None:
                            # Mixed, index (no ComponentFunctionSpace)
                            if fs.index == i:
                                tensor[i, j].set_local_diagonal_entries(bc.nodes)
                        elif fs.component is not None:
                            # ComponentFunctionSpace, check parent index
                            if fs.parent.index is not None:
                                # Mixed, index doesn't match
                                if fs.parent.index != i:
                                    continue
                            # Index matches
                            tensor[i, j].set_local_diagonal_entries(bc.nodes, idx=fs.component)
                        elif fs.index is None:
                            tensor[i, j].set_local_diagonal_entries(bc.nodes)
                        else:
                            raise RuntimeError("Unhandled BC case")
        if bcs is not None and is_vec:
            for bc in bcs:
                bc.apply(result_function)
        if is_mat:
            # Queue up matrix assembly (after we've done all the other operations)
            tensor.assemble()
        return result()

    thunk = assembly_cache._cache_thunk(thunk, f, result(), form_compiler_parameters)

    if is_mat:
        result_matrix._assembly_callback = thunk
        return result()
    else:
        return thunk(bcs)