Source code for sfepy.discrete.fem.poly_spaces

from __future__ import absolute_import
import numpy as nm
import numpy.linalg as nla

from sfepy.base.base import assert_, Struct
from sfepy.discrete import PolySpace
from sfepy.linalg import combine, insert_strided_axis
from six.moves import range
from functools import reduce

# Requires fixed vertex numbering!
vertex_maps = {3 : [[0, 0, 0],
                    [1, 0, 0],
                    [1, 1, 0],
                    [0, 1, 0],
                    [0, 0, 1],
                    [1, 0, 1],
                    [1, 1, 1],
                    [0, 1, 1]],
               2 : [[0, 0],
                    [1, 0],
                    [1, 1],
                    [0, 1]],
               1 : [[0],
                    [1]],
               0 : [[0]]}

[docs] class LagrangeNodes(Struct): """Helper class for defining nodes of Lagrange elements."""
[docs] @staticmethod def append_edges(nodes, nts, iseq, nt, edges, order): delta = 1.0 / float(order) for ii, edge in enumerate(edges): n1 = nodes[edge[0],:].copy() n2 = nodes[edge[1],:].copy() for ie in range(order - 1): c2 = ie + 1 c1 = order - c2 nts[iseq] = [nt, ii] aux = [int(round(tmp)) for tmp in delta * (c1 * n1 + c2 * n2)] nodes[iseq,:] = aux iseq += 1 return iseq
[docs] @staticmethod def append_faces(nodes, nts, iseq, nt, faces, order): delta = 1.0 / float(order) for ii, face in enumerate(faces): n1 = nodes[face[0],:].copy() n2 = nodes[face[1],:].copy() n3 = nodes[face[2],:].copy() for i1 in range(order - 2): for i2 in range(order - 2 - i1): c3 = i1 + 1 c2 = i2 + 1 c1 = order - c3 - c2 nts[iseq] = [nt, ii] aux = [int(round(tmp)) for tmp in delta * (c1 * n1 + c2 * n2 + c3 * n3)] nodes[iseq,:] = aux iseq += 1 return iseq
[docs] @staticmethod def append_bubbles(nodes, nts, iseq, nt, order): delta = 1.0 / float(order) n1 = nodes[0,:].copy() n2 = nodes[1,:].copy() n3 = nodes[2,:].copy() n4 = nodes[3,:].copy() for i1 in range(order - 3): for i2 in range(order - 3): for i3 in range(order - 3 - i1 - i2): c4 = i1 + 1 c3 = i2 + 1 c2 = i3 + 1 c1 = order - c4 - c3 - c2 nts[iseq] = [nt, 0] aux = [int(round(tmp)) for tmp in delta * (c1 * n1 + c2 * n2 + c3 * n3 + c4 * n4)] nodes[iseq,:] = aux iseq += 1 return iseq
[docs] @staticmethod def append_tp_edges(nodes, nts, iseq, nt, edges, ao): delta = 1.0 / float(ao) for ii, edge in enumerate(edges): n1 = nodes[edge[0],:].copy() n2 = nodes[edge[1],:].copy() for ie in range(ao - 1): c2 = ie + 1 c1 = ao - c2 nts[iseq] = [nt, ii] aux = [int(round(tmp)) for tmp in delta * (c1 * n1 + c2 * n2)] nodes[iseq,:] = aux iseq += 1 return iseq
[docs] @staticmethod def append_tp_faces(nodes, nts, iseq, nt, faces, ao): delta = 1.0 / (float(ao) ** 2) for ii, face in enumerate(faces): n1 = nodes[face[0],:].copy() n2 = nodes[face[1],:].copy() n3 = nodes[face[2],:].copy() n4 = nodes[face[3],:].copy() for i1 in range(ao - 1): for i2 in range(ao - 1): c4 = i1 + 1 c3 = i2 + 1 c2 = ao - c4 c1 = ao - c3 nts[iseq] = [nt, ii] aux = [int(round(tmp)) for tmp in delta * (c1 * c2 * n1 + c2 * c3 * n2 + c3 * c4 * n3 + c4 * c1 * n4)] nodes[iseq,:] = aux iseq += 1 return iseq
[docs] @staticmethod def append_tp_bubbles(nodes, nts, iseq, nt, ao): delta = 1.0 / (float(ao) ** 3) n1 = nodes[0,:].copy() n2 = nodes[1,:].copy() n3 = nodes[2,:].copy() n4 = nodes[3,:].copy() n5 = nodes[4,:].copy() n6 = nodes[5,:].copy() n7 = nodes[6,:].copy() n8 = nodes[7,:].copy() for i1 in range(ao - 1): for i2 in range(ao - 1): for i3 in range(ao - 1): c6 = i1 + 1 c5 = i2 + 1 c4 = i3 + 1 c3 = ao - c6 c2 = ao - c5 c1 = ao - c4 nts[iseq] = [nt, 0] aux = [int(round(tmp)) for tmp in delta * (c1 * c2 * c3 * n1 + c4 * c2 * c3 * n2 + c5 * c4 * c3 * n3 + c1 * c3 * c5 * n4 + c1 * c2 * c6 * n5 + c4 * c2 * c6 * n6 + c5 * c4 * c6 * n7 + c1 * c6 * c5 * n8)] nodes[iseq,:] = aux iseq += 1 return iseq
[docs] class NodeDescription(Struct): """ Describe FE nodes defined on different parts of a reference element. """ def _describe_facets(self, ii): nts = self.node_types[ii] ik = nm.where(nts[1:,1] > nts[:-1,1])[0] if len(ik) == 0: ifacets = None n_dof = 0 else: ii = ii.astype(nm.int32) ik = nm.r_[0, ik + 1, nts.shape[0]] ifacets = [ii[ik[ir] : ik[ir+1]] for ir in range(len(ik) - 1)] n_dof = len(ifacets[0]) return ifacets, n_dof def _describe_other(self, ii): if len(ii): return ii, len(ii) else: return None, 0 def _get_facet_nodes(self, ifacets, nodes): if ifacets is None: return None else: return [nodes[ii] for ii in ifacets] def _get_nodes(self, ii, nodes): if ii is None: return None else: return nodes[ii] def __init__(self, node_types, nodes): self.node_types = node_types # Vertex nodes. ii = nm.where(node_types[:,0] == 0)[0] self.vertex, self.n_vertex_nod = self._describe_other(ii) self.vertex_nodes = self._get_nodes(self.vertex, nodes) # Edge nodes. ii = nm.where(node_types[:,0] == 1)[0] self.edge, self.n_edge_nod = self._describe_facets(ii) self.edge_nodes = self._get_facet_nodes(self.edge, nodes) # Face nodes. ii = nm.where(node_types[:,0] == 2)[0] self.face, self.n_face_nod = self._describe_facets(ii) self.face_nodes = self._get_facet_nodes(self.face, nodes) # Bubble nodes. ii = nm.where(node_types[:,0] == 3)[0] self.bubble, self.n_bubble_nod = self._describe_other(ii) self.bubble_nodes = self._get_nodes(self.bubble, nodes)
[docs] def has_extra_nodes(self): """ Return True if the element has some edge, face or bubble nodes. """ return (self.n_edge_nod + self.n_face_nod + self.n_bubble_nod) > 0
[docs] class FEPolySpace(PolySpace): """ Base for FE polynomial space classes. """
[docs] def get_mtx_i(self): return self.mtx_i
[docs] def describe_nodes(self): return NodeDescription(self.nts, self.nodes)
[docs] class LagrangePolySpace(FEPolySpace):
[docs] def create_context(self, cmesh, eps, check_errors, i_max, newton_eps, tdim=None): from sfepy.discrete.fem.extmods.bases import CLagrangeContext ref_coors = self.geometry.coors if cmesh is not None: mesh_coors = cmesh.coors conn = cmesh.get_conn(cmesh.tdim, 0) mesh_conn = conn.indices.reshape(cmesh.n_el, -1).astype(nm.int32) if tdim is None: tdim = cmesh.tdim else: mesh_coors = mesh_conn = None if tdim is None: raise ValueError('supply either cmesh or tdim!') ctx = CLagrangeContext(order=self.order, tdim=tdim, nodes=self.nodes, ref_coors=ref_coors, mesh_coors=mesh_coors, mesh_conn=mesh_conn, mtx_i=self.get_mtx_i(), eps=eps, check_errors=check_errors, i_max=i_max, newton_eps=newton_eps) return ctx
def _eval_base(self, coors, diff=0, ori=None, suppress_errors=False, eps=1e-15): """ See :func:`PolySpace.eval_base()`. """ if diff == 2: base = self._eval_hessian(coors) else: base = self.eval_ctx.evaluate(coors, diff=diff, eps=eps, check_errors=not suppress_errors) return base
[docs] class LagrangeSimplexPolySpace(LagrangePolySpace): """Lagrange polynomial space on a simplex domain.""" name = 'lagrange_simplex' def __init__(self, name, geometry, order, init_context=True): PolySpace.__init__(self, name, geometry, order) n_v = geometry.n_vertex mtx = nm.ones((n_v, n_v), nm.float64) mtx[0:n_v-1,:] = nm.transpose(geometry.coors) self.mtx_i = nm.ascontiguousarray(nla.inv(mtx)) self.rhs = nm.ones((n_v,), nm.float64) self.nodes, self.nts, node_coors = self._define_nodes() self.node_coors = nm.ascontiguousarray(node_coors) self.n_nod = self.nodes.shape[0] if init_context: self.eval_ctx = self.create_context(None, 0, 1e-15, 100, 1e-8, tdim=n_v - 1) else: self.eval_ctx = None def _define_nodes(self): # Factorial. fac = lambda n : reduce(lambda a, b : a * (b + 1), range(n), 1) geometry = self.geometry n_v, dim = geometry.n_vertex, geometry.dim order = self.order n_nod = fac(order + dim) // (fac(order) * fac(dim)) ## print n_nod, gd nodes = nm.zeros((n_nod, n_v), nm.int32) nts = nm.zeros((n_nod, 2), nm.int32) if order == 0: nts[0,:] = [3, 0] nodes[0,:] = nm.zeros((n_v,), nm.int32) else: iseq = 0 # Vertex nodes. nts[0:n_v,0] = 0 nts[0:n_v,1] = nm.arange(n_v, dtype = nm.int32) aux = order * nm.identity(n_v, dtype = nm.int32) nodes[iseq:iseq+n_v,:] = aux iseq += n_v if dim == 0: pass elif dim == 1: iseq = LagrangeNodes.append_edges(nodes, nts, iseq, 3, [[0, 1]], order) elif dim == 2: iseq = LagrangeNodes.append_edges(nodes, nts, iseq, 1, geometry.edges, order) iseq = LagrangeNodes.append_faces(nodes, nts, iseq, 3, [[0, 1, 2]], order) elif dim == 3: iseq = LagrangeNodes.append_edges(nodes, nts, iseq, 1, geometry.edges, order) iseq = LagrangeNodes.append_faces(nodes, nts, iseq, 2, geometry.faces, order) iseq = LagrangeNodes.append_bubbles(nodes, nts, iseq, 3, order) else: raise NotImplementedError ## print nm.concatenate((nts, nodes), 1) # Check orders. orders = nm.sum(nodes, 1) if not nm.all(orders == order): raise AssertionError('wrong orders! (%d == all of %s)' % (order, orders)) # Coordinates of the nodes. if order == 0: tmp = nm.ones((n_nod, n_v), nm.int32) node_coors = nm.dot(tmp, geometry.coors) / n_v else: node_coors = nm.dot(nodes, geometry.coors) / order return nodes, nts, node_coors def _eval_hessian(self, coors): """ Evaluate the second derivatives of the basis. """ def get_bc(coor): rhs = nm.concatenate((coor, [1])) bc = nm.dot(self.mtx_i, rhs) return bc def get_val(bc, node, omit=[]): val = nm.ones(1, nm.float64) for i1 in range(bc.shape[0]): if i1 in omit: continue for i2 in range(node[i1]): val *= (self.order * bc[i1] - i2) / (i2 + 1.0) return val def get_der(bc1, node1, omit=[]): val = nm.zeros(1, nm.float64) for i1 in range(node1): if i1 in omit: continue aux = nm.ones(1, nm.float64) for i2 in range(node1): if (i1 == i2) or (i2 in omit): continue aux *= (self.order * bc1 - i2) / (i2 + 1.0) val += aux * self.order / (i1 + 1.0) return val n_v = self.mtx_i.shape[0] dim = n_v - 1 mi = self.mtx_i[:, :dim] bfgg = nm.zeros((coors.shape[0], dim, dim, self.n_nod), dtype=nm.float64) for ic, coor in enumerate(coors): bc = get_bc(coor) for ii, node in enumerate(self.nodes): for ig1, bc1 in enumerate(bc): # 1. derivative w.r.t. bc1. for ig2, bc2 in enumerate(bc): # 2. derivative w.r.t. bc2. if ig1 == ig2: val = get_val(bc, node, omit=[ig1]) vv = 0.0 for i1 in range(node[ig1]): aux = get_der(bc2, node[ig2], omit=[i1]) vv += aux * self.order / (i1 + 1.0) val *= vv else: val = get_val(bc, node, omit=[ig1, ig2]) val *= get_der(bc1, node[ig1]) val *= get_der(bc2, node[ig2]) bfgg[ic, :, :, ii] += val * mi[ig1] * mi[ig2][:, None] return bfgg
[docs] class LagrangeSimplexBPolySpace(LagrangeSimplexPolySpace): """Lagrange polynomial space with forced bubble function on a simplex domain.""" name = 'lagrange_simplex_bubble' def __init__(self, name, geometry, order, init_context=True): LagrangeSimplexPolySpace.__init__(self, name, geometry, order, init_context=False) nodes, nts, node_coors = self.nodes, self.nts, self.node_coors shape = [nts.shape[0] + 1, 2] nts = nm.resize(nts, shape) nts[-1,:] = [3, 0] shape = [nodes.shape[0] + 1, nodes.shape[1]] nodes = nm.resize(nodes, shape) # Make a 'hypercubic' (cubic in 2D) node. nodes[-1,:] = 1 n_v = self.geometry.n_vertex tmp = nm.ones((n_v,), nm.int32) node_coors = nm.vstack((node_coors, nm.dot(tmp, self.geometry.coors) / n_v)) self.nodes, self.nts = nodes, nts self.node_coors = nm.ascontiguousarray(node_coors) self.bnode = nodes[-1:,:] self.n_nod = self.nodes.shape[0] if init_context: self.eval_ctx = self.create_context(None, 0, 1e-15, 100, 1e-8, tdim=n_v - 1) else: self.eval_ctx = None
[docs] def create_context(self, *args, **kwargs): ctx = LagrangePolySpace.create_context(self, *args, **kwargs) ctx.is_bubble = 1 return ctx
[docs] class LagrangeTensorProductPolySpace(LagrangePolySpace): """Lagrange polynomial space on a tensor product domain.""" name = 'lagrange_tensor_product' def __init__(self, name, geometry, order, init_context=True): PolySpace.__init__(self, name, geometry, order) g1d = Struct(n_vertex = 2, dim = 1, coors = self.bbox[:,0:1].copy()) self.ps1d = LagrangeSimplexPolySpace('P_aux', g1d, order, init_context=False) self.nodes, self.nts, node_coors = self._define_nodes() self.node_coors = nm.ascontiguousarray(node_coors) self.n_nod = self.nodes.shape[0] if init_context: tdim = int(nm.sqrt(geometry.n_vertex)) self.eval_ctx = self.create_context(None, 0, 1e-15, 100, 1e-8, tdim=tdim) else: self.eval_ctx = None def _define_nodes(self): geometry = self.geometry order = self.order n_v, dim = geometry.n_vertex, geometry.dim vertex_map = order * nm.array(vertex_maps[dim], dtype=nm.int32) n_nod = (order + 1) ** dim nodes = nm.zeros((n_nod, 2 * dim), nm.int32) nts = nm.zeros((n_nod, 2), nm.int32) if order == 0: nts[0,:] = [3, 0] nodes[0,:] = nm.zeros((n_nod,), nm.int32) else: iseq = 0 # Vertex nodes. nts[0:n_v,0] = 0 nts[0:n_v,1] = nm.arange(n_v, dtype=nm.int32) if dim == 3: for ii in range(n_v): i1, i2, i3 = vertex_map[ii] nodes[iseq,:] = [order - i1, i1, order - i2, i2, order - i3, i3] iseq += 1 elif dim == 2: for ii in range(n_v): i1, i2 = vertex_map[ii] nodes[iseq,:] = [order - i1, i1, order - i2, i2] iseq += 1 else: for ii in range(n_v): i1 = vertex_map[ii][0] nodes[iseq,:] = [order - i1, i1] iseq += 1 if dim == 1: iseq = LagrangeNodes.append_tp_edges(nodes, nts, iseq, 3, [[0, 1]], order) elif dim == 2: iseq = LagrangeNodes.append_tp_edges(nodes, nts, iseq, 1, geometry.edges, order) iseq = LagrangeNodes.append_tp_faces(nodes, nts, iseq, 3, [[0, 1, 2, 3]], order) elif dim == 3: iseq = LagrangeNodes.append_tp_edges(nodes, nts, iseq, 1, geometry.edges, order) iseq = LagrangeNodes.append_tp_faces(nodes, nts, iseq, 2, geometry.faces, order) iseq = LagrangeNodes.append_tp_bubbles(nodes, nts, iseq, 3, order) else: raise NotImplementedError # Check orders. orders = nm.sum(nodes, 1) if not nm.all(orders == order * dim): raise AssertionError('wrong orders! (%d == all of %s)' % (order * dim, orders)) # Coordinates of the nodes. if order == 0: tmp = nm.ones((n_nod, n_v), nm.int32) node_coors = nm.dot(tmp, geometry.coors) / n_v else: c_min, c_max = self.bbox[:,0] cr = nm.arange(2 * dim) node_coors = (nodes[:,cr[::2]] * c_min + nodes[:,cr[1::2]] * c_max) / order return nodes, nts, node_coors def _eval_base_debug(self, coors, diff=False, ori=None, suppress_errors=False, eps=1e-15): """Python version of eval_base().""" dim = self.geometry.dim ev = self.ps1d.eval_base if diff: base = nm.ones((coors.shape[0], dim, self.n_nod), dtype=nm.float64) for ii in range(dim): self.ps1d.nodes = self.nodes[:,2*ii:2*ii+2].copy() self.ps1d.n_nod = self.n_nod for iv in range(dim): if ii == iv: base[:,iv:iv+1,:] *= ev(coors[:,ii:ii+1].copy(), diff=True, suppress_errors=suppress_errors, eps=eps) else: base[:,iv:iv+1,:] *= ev(coors[:,ii:ii+1].copy(), diff=False, suppress_errors=suppress_errors, eps=eps) else: base = nm.ones((coors.shape[0], 1, self.n_nod), dtype=nm.float64) for ii in range(dim): self.ps1d.nodes = self.nodes[:,2*ii:2*ii+2].copy() self.ps1d.n_nod = self.n_nod base *= ev(coors[:,ii:ii+1].copy(), diff=diff, suppress_errors=suppress_errors, eps=eps) return base def _eval_hessian(self, coors): """ Evaluate the second derivatives of the basis. """ evh = self.ps1d.eval_base dim = self.geometry.dim bfgg = nm.zeros((coors.shape[0], dim, dim, self.n_nod), dtype=nm.float64) v0s = [] v1s = [] v2s = [] for ii in range(dim): self.ps1d.nodes = self.nodes[:,2*ii:2*ii+2].copy() self.ps1d.n_nod = self.n_nod ev = self.ps1d.create_context(None, 0, 1e-15, 100, 1e-8, tdim=1).evaluate v0s.append(ev(coors[:, ii:ii+1].copy())[:, 0, :]) v1s.append(ev(coors[:, ii:ii+1].copy(), diff=1)[:, 0, :]) v2s.append(evh(coors[:, ii:ii+1], diff=2)[:, 0, 0, :]) for ir in range(dim): vv = v2s[ir] # Destroys v2s! for ik in range(dim): if ik == ir: continue vv *= v0s[ik] bfgg[:, ir, ir, :] = vv for ic in range(dim): if ic == ir: continue val = v1s[ir] * v1s[ic] for ik in range(dim): if (ik == ir) or (ik == ic): continue val *= v0s[ik] bfgg[:, ir, ic, :] += val return bfgg
[docs] def get_mtx_i(self): return self.ps1d.mtx_i
[docs] class SerendipityTensorProductPolySpace(FEPolySpace): """ Serendipity polynomial space using Lagrange functions. Notes ----- - Orders >= 4 (with bubble functions) are not supported. - Does not use CLagrangeContext, basis functions are hardcoded. - `self.nodes`, `self.node_coors` are not used for basis evaluation and assembling. """ name = 'serendipity_tensor_product' supported_orders = {1, 2, 3} from sfepy.discrete.fem._serendipity import all_bfs def __init__(self, name, geometry, order): import sympy as sm if geometry.dim < 2: raise ValueError('serendipity elements need dimension 2 or 3! (%d)' % geometry.dim) if order not in self.supported_orders: raise ValueError('serendipity elements support only orders %s! (%d)' % (self.supported_orders, order)) PolySpace.__init__(self, name, geometry, order) self.nodes, self.nts, self.node_coors = self._define_nodes() self.n_nod = self.nodes.shape[0] bfs = self.all_bfs[geometry.dim][order] self.bfs = bfs[0] self.bfgs = bfs[1] x, y, z = sm.symbols('x y z') vs = [x, y, z][:geometry.dim] self._bfs = [sm.lambdify(vs, bf) for bf in self.bfs] self._bfgs = [[sm.lambdify(vs, bfg) for bfg in bfgs] for bfgs in self.bfgs]
[docs] def create_context(self, cmesh, eps, check_errors, i_max, newton_eps, tdim=None): pass
def _define_nodes(self): geometry = self.geometry order = self.order n_v, dim = geometry.n_vertex, geometry.dim vertex_map = order * nm.array(vertex_maps[dim], dtype=nm.int32) # Only for orders 1, 2, 3! if dim == 2: n_nod = 4 * self.order else: n_nod = 8 + 12 * (self.order - 1) nodes = nm.zeros((n_nod, 2 * dim), nm.int32) nts = nm.zeros((n_nod, 2), nm.int32) if order == 0: nts[0, :] = [3, 0] nodes[0, :] = nm.zeros((n_nod,), nm.int32) else: iseq = 0 # Vertex nodes. nts[0:n_v, 0] = 0 nts[0:n_v, 1] = nm.arange(n_v, dtype=nm.int32) if dim == 3: for ii in range(n_v): i1, i2, i3 = vertex_map[ii] nodes[iseq, :] = [order - i1, i1, order - i2, i2, order - i3, i3] iseq += 1 else: # dim == 2: for ii in range(n_v): i1, i2 = vertex_map[ii] nodes[iseq, :] = [order - i1, i1, order - i2, i2] iseq += 1 if dim == 2: iseq = LagrangeNodes.append_tp_edges(nodes, nts, iseq, 1, geometry.edges, order) elif dim == 3: iseq = LagrangeNodes.append_tp_edges(nodes, nts, iseq, 1, geometry.edges, order) else: raise NotImplementedError # Coordinates of the nodes. c_min, c_max = self.bbox[:, 0] cr = nm.arange(2 * dim) node_coors = (nodes[:, cr[::2]] * c_min + nodes[:, cr[1::2]] * c_max) / order return nodes, nts, nm.ascontiguousarray(node_coors) def _eval_base(self, coors, diff=0, ori=None, suppress_errors=False, eps=1e-15): """ See :func:`PolySpace.eval_base()`. """ dim = self.geometry.dim if diff: bdim = dim else: bdim = 1 base = nm.empty((coors.shape[0], bdim, self.n_nod), dtype=nm.float64) if diff == 0: for ib, bf in enumerate(self._bfs): base[:, 0, ib] = bf(*coors.T) elif diff == 1: for ib, bfg in enumerate(self._bfgs): for ig in range(dim): base[:, ig, ib] = bfg[ig](*coors.T) else: raise NotImplementedError return base
[docs] class LobattoTensorProductPolySpace(FEPolySpace): """ Hierarchical polynomial space using Lobatto functions. Each row of the `nodes` attribute defines indices of Lobatto functions that need to be multiplied together to evaluate the corresponding shape function. This defines the ordering of basis functions on the reference element. """ name = 'lobatto_tensor_product' def __init__(self, name, geometry, order): PolySpace.__init__(self, name, geometry, order) aux = self._define_nodes() self.nodes, self.nts, node_coors, self.face_axes, self.sfnodes = aux self.node_coors = nm.ascontiguousarray(node_coors) self.n_nod = self.nodes.shape[0] aux = nm.where(self.nodes > 0, self.nodes, 1) self.node_orders = nm.prod(aux, axis=1) self.edge_indx = nm.where(self.nts[:, 0] == 1)[0] self.face_indx = nm.where(self.nts[:, 0] == 2)[0] self.face_axes_nodes = self._get_face_axes_nodes(self.face_axes) def _get_counts(self): order = self.order dim = self.geometry.dim n_nod = (order + 1) ** dim n_per_edge = (order - 1) n_per_face = (order - 1) ** (dim - 1) n_bubble = (order - 1) ** dim return n_nod, n_per_edge, n_per_face, n_bubble def _define_nodes(self): geometry = self.geometry order = self.order n_v, dim = geometry.n_vertex, geometry.dim n_nod, n_per_edge, n_per_face, n_bubble = self._get_counts() nodes = nm.zeros((n_nod, dim), nm.int32) nts = nm.zeros((n_nod, 2), nm.int32) # Vertex nodes. nts[0:n_v, 0] = 0 nts[0:n_v, 1] = nm.arange(n_v, dtype=nm.int32) nodes[0:n_v] = nm.array(vertex_maps[dim], dtype=nm.int32) ii = n_v # Edge nodes. if (dim > 1) and (n_per_edge > 0): ik = nm.arange(2, order + 1, dtype=nm.int32) zo = nm.zeros((n_per_edge, 2), dtype=nm.int32) zo[:, 1] = 1 for ie, edge in enumerate(geometry.edges): n1, n2 = nodes[edge] ifix = nm.where(n1 == n2)[0] irun = nm.where(n1 != n2)[0][0] ic = n1[ifix] nodes[ii:ii + n_per_edge, ifix] = zo[:, ic] nodes[ii:ii + n_per_edge, irun] = ik nts[ii:ii + n_per_edge] = [[1, ie]] ii += n_per_edge # 3D face nodes. face_axes = [] sfnodes = None if (dim == 3) and (n_per_face > 0): n_face = len(geometry.faces) sfnodes = nm.zeros((n_per_face * n_face, dim), nm.int32) ii0 = ii ik = nm.arange(2, order + 1, dtype=nm.int32) zo = nm.zeros((n_per_face, 2), dtype=nm.int32) zo[:, 1] = 1 for ifa, face in enumerate(geometry.faces): ns = nodes[face] diff = nm.diff(ns, axis=0) asum = nm.abs(diff).sum(axis=0) ifix = nm.where(asum == 0)[0][0] ic = ns[0, ifix] irun1 = nm.where(asum == 2)[0][0] irun2 = nm.where(asum == 1)[0][0] iy, ix = nm.meshgrid(ik, ik) nodes[ii:ii + n_per_face, ifix] = zo[:, ic] nodes[ii:ii + n_per_face, irun1] = ix.ravel() nodes[ii:ii + n_per_face, irun2] = iy.ravel() nts[ii:ii + n_per_face] = [[2, ifa]] ij = ii - ii0 sfnodes[ij:ij + n_per_face, ifix] = zo[:, ic] sfnodes[ij:ij + n_per_face, irun1] = iy.ravel() sfnodes[ij:ij + n_per_face, irun2] = ix.ravel() face_axes.append([irun1, irun2]) ii += n_per_face face_axes = nm.array(face_axes) # Bubble nodes. if n_bubble > 0: ik = nm.arange(2, order + 1, dtype=nm.int32) nodes[ii:] = nm.array([aux for aux in combine([ik] * dim)]) nts[ii:ii + n_bubble] = [[3, 0]] ii += n_bubble assert_(ii == n_nod) # Coordinates of the "nodes". All nodes on a facet have the same # coordinates - the centre of the facet. c_min, c_max = self.bbox[:, 0] node_coors = nm.zeros(nodes.shape, dtype=nm.float64) node_coors[:n_v] = nodes[:n_v] if (dim > 1) and (n_per_edge > 0): ie = nm.where(nts[:, 0] == 1)[0] node_coors[ie] = node_coors[geometry.edges[nts[ie, 1]]].mean(1) if (dim == 3) and (n_per_face > 0): ifa = nm.where(nts[:, 0] == 2)[0] node_coors[ifa] = node_coors[geometry.faces[nts[ifa, 1]]].mean(1) if n_bubble > 0: ib = nm.where(nts[:, 0] == 3)[0] node_coors[ib] = node_coors[geometry.conn].mean(0) return nodes, nts, node_coors, face_axes, sfnodes def _get_face_axes_nodes(self, face_axes): if not len(face_axes): return None nodes = self.nodes[self.face_indx] n_per_face = self._get_counts()[2] anodes = nm.tile(nodes[:n_per_face, face_axes[0]], (6, 1)) return anodes def _eval_base(self, coors, diff=False, ori=None, suppress_errors=False, eps=1e-15): """ See PolySpace.eval_base(). """ from .extmods.lobatto_bases import eval_lobatto_tensor_product as ev c_min, c_max = self.bbox[:, 0] base = ev(coors, self.nodes, c_min, c_max, self.order, diff) if ori is not None: ebase = nm.tile(base, (ori.shape[0], 1, 1, 1)) if self.edge_indx.shape[0]: # Orient edge functions. ie, ii = nm.where(ori[:, self.edge_indx] == 1) ii = self.edge_indx[ii] ebase[ie, :, :, ii] *= -1.0 if self.face_indx.shape[0]: # Orient face functions. fori = ori[:, self.face_indx] # ... normal axis order ie, ii = nm.where((fori == 1) | (fori == 2)) ii = self.face_indx[ii] ebase[ie, :, :, ii] *= -1.0 # ... swapped axis order sbase = ev(coors, self.sfnodes, c_min, c_max, self.order, diff) sbase = insert_strided_axis(sbase, 0, ori.shape[0]) # ...overwrite with swapped axes basis. ie, ii = nm.where(fori >= 4) ii2 = self.face_indx[ii] ebase[ie, :, :, ii2] = sbase[ie, :, :, ii] # ...deal with orientation. ie, ii = nm.where((fori == 5) | (fori == 6)) ii = self.face_indx[ii] ebase[ie, :, :, ii] *= -1.0 base = ebase return base
[docs] class BernsteinSimplexPolySpace(FEPolySpace): """ Bernstein polynomial space on simplex domains. Notes ----- Naive proof-of-concept implementation, does not use recurrent formulas or Duffy transformation to obtain tensor product structure. """ name = 'bernstein_simplex' def __init__(self, name, geometry, order): PolySpace.__init__(self, name, geometry, order) self.nodes, self.nts, self.node_coors = self._define_nodes() self.n_nod = self.nodes.shape[0] self.eval_ctx = None def _define_nodes(self): nodes, nts, node_coors = LagrangeSimplexPolySpace._define_nodes(self) return nodes, nts, node_coors @staticmethod def _get_barycentric(coors): dim = coors.shape[1] bcoors = nm.empty((coors.shape[0], dim + 1)) bcoors[:, 0] = 1.0 - coors.sum(axis=1) bcoors[:, 1:] = coors return bcoors def _eval_base(self, coors, diff=False, ori=None, suppress_errors=False, eps=1e-15): """ See PolySpace.eval_base(). """ from scipy.special import factorial dim = self.geometry.dim if diff: bdim = dim bgrad = nm.zeros((dim + 1, dim), dtype=nm.float64) bgrad[0] = -1 bgrad[1:] = nm.eye(dim) else: bdim = 1 base = nm.ones((coors.shape[0], bdim, self.n_nod), dtype=nm.float64) if dim == 0: return base bcoors = self._get_barycentric(coors) fs = factorial(nm.arange(0, self.order + 1)) of = fs[-1] if not diff: for ii, node in enumerate(self.nodes): coef = of / nm.prod(fs[node]) val = coef * nm.prod(nm.power(bcoors, node), axis=1) base[:, 0, ii] = val else: for ii, node in enumerate(self.nodes): coef = of / nm.prod(fs[node]) for ider in range(dim): dval = 0.0 for ib in range(dim + 1): ex = node[ib] val = coef for im in range(dim + 1): if ib == im: val *= (ex * nm.power(bcoors[:, im], ex - 1) * bgrad[ib, ider]) else: val *= nm.power(bcoors[:, im], node[im]) dval += val base[:, ider, ii] = dval return base
[docs] class BernsteinTensorProductPolySpace(FEPolySpace): """ Bernstein polynomial space. Each row of the `nodes` attribute defines indices of 1D Bernstein basis functions that need to be multiplied together to evaluate the corresponding shape function. This defines the ordering of basis functions on the reference element. """ name = 'bernstein_tensor_product' def __init__(self, name, geometry, order): PolySpace.__init__(self, name, geometry, order) self.nodes, self.nts, self.node_coors = self._define_nodes() self.n_nod = self.nodes.shape[0] self.eval_ctx = None def _define_nodes(self): nn, nts, node_coors = LagrangeTensorProductPolySpace._define_nodes(self) nodes = nn[:, 1::2] return nodes, nts, node_coors def _eval_base(self, coors, diff=False, ori=None, suppress_errors=False, eps=1e-15): """ See PolySpace.eval_base(). """ from sfepy.discrete.iga.extmods.igac import eval_bernstein_basis as ev dim = self.geometry.dim if diff: bdim = dim else: bdim = 1 base = nm.ones((coors.shape[0], bdim, self.n_nod), dtype=nm.float64) degree = self.order n_efuns_max = degree + 1 for iq, qp in enumerate(coors): B = nm.empty((dim, n_efuns_max), dtype=nm.float64) dB_dxi = nm.empty((dim, n_efuns_max), dtype=nm.float64) for ii in range(dim): ev(B[ii, :], dB_dxi[ii, :], qp[ii], degree) if not diff: for ii, ni in enumerate(self.nodes.T): base[iq, 0, :] *= B[ii, ni] else: for ii, ni in enumerate(self.nodes.T): for iv in range(bdim): if ii == iv: base[iq, iv, :] *= dB_dxi[ii, ni] else: base[iq, iv, :] *= B[ii, ni] return base
[docs] def get_lgl_nodes(p): """ Compute the Legendre-Gauss-Lobatto nodes and weights. """ from numpy.polynomial.legendre import legvander # Use the Chebyshev-Gauss-Lobatto nodes as the first guess. xs = nm.cos(nm.pi * nm.arange(p + 1) / p) eps = nm.finfo(nm.float64).eps xs0 = 2.0 while nm.linalg.norm(xs - xs0, ord=nm.inf) > eps: xs0 = xs V = legvander(xs, p) xs = xs0 - (xs * V[:, p] - V[:,p-1]) / ((p+1) * V[:,p]) ws = 2.0 / (p * (p+1) * V[:,p]**2) return xs, ws
[docs] def eval_lagrange1d_basis(coors, ncoors): n_nod = len(ncoors) n_coors = len(coors) val = nm.ones((n_coors, n_nod), dtype=nm.float64) dval = nm.zeros((n_coors, n_nod), dtype=nm.float64) for ib in range(n_nod): for ic in range(n_nod): if ib != ic: val[:, ib] *= ((coors - ncoors[ic]) / (ncoors[ib] - ncoors[ic])) for ik in range(n_nod): if ib == ik: continue aux = 1.0 / (ncoors[ib] - ncoors[ik]) for ic in range(n_nod): if (ib != ic) and (ik != ic): aux *= ((coors - ncoors[ic]) / (ncoors[ib] - ncoors[ic])) dval[:, ib] += aux return val, dval
[docs] class SEMTensorProductPolySpace(FEPolySpace): """ Spectral element method polynomial space = Lagrange polynomial space with Legendre-Gauss-Lobatto nodes. The same nodes and corresponding weights should be used for numerical quadrature to obtain a diagonal mass matrix. """ name = 'sem_tensor_product' def __init__(self, name, geometry, order, init_context=True): PolySpace.__init__(self, name, geometry, order) (self.nodes, self.nts, node_coors, self.node_weights, self.node_coors1d, self.weights1d) = self._define_nodes() self.node_coors = nm.ascontiguousarray(node_coors) self.n_nod = self.nodes.shape[0] self.eval_ctx = None def _define_nodes(self): nn, nts, node_coors = LagrangeTensorProductPolySpace._define_nodes(self) nodes = nn[:, 1::2] node_coors1d, weights1d = get_lgl_nodes(self.order) # Transform node_coors1d from [1, -1] to [0, 1]. node_coors1d = 0.5 * (1 - node_coors1d) weights1d *= 0.5 node_weights = nm.ones_like(node_coors[:, 0]) for ii, ni in enumerate(nodes.T): node_coors[:, ii] = node_coors1d[ni] node_weights[:] *= weights1d[ni] return nodes, nts, node_coors, node_weights, node_coors1d, weights1d def _eval_base(self, coors, diff=0, ori=None, suppress_errors=False, eps=1e-15): """ See :func:`PolySpace.eval_base()`. """ dim = self.geometry.dim bdim = dim if diff else 1 assert diff in (0, 1) out = nm.ones((coors.shape[0], bdim, self.n_nod), dtype=nm.float64) vals = [] dvals = [] for ii in range(dim): b1d, db1d = eval_lagrange1d_basis(coors[:, ii], self.node_coors1d) vals.append(b1d) dvals.append(db1d) if diff == 0: for ii, ni in enumerate(self.nodes.T): out[:, 0, :] *= vals[ii][:, ni] else: for ii, ni in enumerate(self.nodes.T): for iv in range(bdim): if ii == iv: out[:, iv, :] *= dvals[ii][:, ni] else: out[:, iv, :] *= vals[ii][:, ni] return out