def test_different_element_interpolation(family1, args1, family2, args2,
cell_type, order):
lower_element = basix.create_element(family1, cell_type, order, *args1)
higher_element = basix.create_element(family2, cell_type, order, *args2)
run_test(lower_element, higher_element, order - 1,
lower_element.value_size)
def test_different_variant_interpolation(cell_type, order, variant1, variant2):
lower_element = basix.create_element(basix.ElementFamily.P, cell_type,
order, variant1)
higher_element = basix.create_element(basix.ElementFamily.P, cell_type,
order, variant2)
run_test(lower_element, higher_element, order, lower_element.value_size)
def test_blocked_interpolation(cell_type, order):
"""Test interpolation of Nedelec's componenets into a Lagrange space."""
nedelec = basix.create_element(basix.ElementFamily.N2E, cell_type, order)
lagrange = basix.create_element(basix.ElementFamily.P, cell_type, order,
basix.LagrangeVariant.gll_isaac)
n_points = nedelec.points
if nedelec.value_size == 2:
n_eval = np.concatenate([n_points[:, 0]**order, n_points[:, 1]**order])
else:
n_eval = np.concatenate(
[n_points[:, 0]**order, 0 * n_points[:, 0], n_points[:, 1]**order])
n_coeffs = nedelec.interpolation_matrix @ n_eval
l_points = lagrange.points
if nedelec.value_size == 2:
values = [l_points[:, 0]**order, l_points[:, 1]**order]
else:
values = [
l_points[:, 0]**order, 0 * l_points[:, 0], l_points[:, 1]**order
]
l_coeffs = np.empty(lagrange.dim * nedelec.value_size)
for i, v in enumerate(values):
l_coeffs[i::nedelec.value_size] = v
# Test interpolation from Nedelec to blocked Lagrange
i_m = basix.compute_interpolation_operator(nedelec, lagrange)
assert np.allclose(l_coeffs, i_m @ n_coeffs)
# Test interpolation from blocked Lagrange to Nedelec
i_m = basix.compute_interpolation_operator(lagrange, nedelec)
assert np.allclose(n_coeffs, i_m @ l_coeffs)
def create_basix_element(ufl_element):
# TODO: EnrichedElement
# TODO: Short/alternative names for elements
if isinstance(ufl_element, ufl.VectorElement):
return BlockedElement(
create_basix_element(ufl_element.sub_elements()[0]),
ufl_element.num_sub_elements())
if isinstance(ufl_element, ufl.TensorElement):
return BlockedElement(
create_basix_element(ufl_element.sub_elements()[0]),
ufl_element.num_sub_elements(), None) # TODO: block shape
if isinstance(ufl_element, ufl.MixedElement):
return MixedElement(
[create_basix_element(e) for e in ufl_element.sub_elements()])
if ufl_element.family() in ufl_to_basix_names:
return BasixElement(
basix.create_element(ufl_to_basix_names[ufl_element.family()],
ufl_element.cell().cellname(),
ufl_element.degree()))
return BasixElement(
basix.create_element(ufl_element.family(),
ufl_element.cell().cellname(),
ufl_element.degree()))
def test_different_order_interpolation_lagrange(cell_type, orders):
lower_element = basix.create_element(basix.ElementFamily.P, cell_type,
orders[0],
basix.LagrangeVariant.gll_warped)
higher_element = basix.create_element(basix.ElementFamily.P, cell_type,
orders[1],
basix.LagrangeVariant.gll_warped)
run_test(lower_element, higher_element, orders[0],
lower_element.value_size)
def test_lagrange(celltype, degree):
lagrange = basix.create_element(basix.ElementFamily.P, celltype[1], degree,
basix.LagrangeVariant.equispaced)
pts = basix.create_lattice(celltype[0], 6, basix.LatticeType.equispaced,
True)
w = lagrange.tabulate(0, pts)[0]
assert (numpy.isclose(numpy.sum(w, axis=1), 1.0).all())
def test_cr2d():
cr2 = basix.create_element(basix.ElementFamily.CR, basix.CellType.triangle,
1)
pts = basix.create_lattice(basix.CellType.triangle, 2,
basix.LatticeType.equispaced, True)
w = cr2.tabulate(0, pts)[0]
print(w.shape)
def test_cr3d():
cr3 = basix.create_element(basix.ElementFamily.CR,
basix.CellType.tetrahedron, 1)
pts = basix.create_lattice(basix.CellType.tetrahedron, 2,
basix.LatticeType.equispaced, True)
w = cr3.tabulate(0, pts)[0]
print(w.shape)
def test_regge_tri2():
# Second order
regge = basix.create_element(basix.ElementFamily.Regge, basix.CellType.triangle, 2)
# tabulate at origin
pts = [[0.0, 0.0]]
w = regge.tabulate(0, pts)[0].reshape(-1, 2, 2)
ref = np.array([[[0., -0.5], [-0.5, 0.]],
[[0., -0.5], [-0.5, -0.]],
[[-0., -0.5], [-0.5, 0.]],
[[-0., 1.5], [1.5, 3.]],
[[0., -1.5], [-1.5, -3.]],
[[-0., 0.5], [0.5, 1.]],
[[3., 1.5], [1.5, -0.]],
[[-3., -1.5], [-1.5, 0.]],
[[1., 0.5], [0.5, -0.]],
[[-0., -0.], [-0., -0.]],
[[0., -0.], [-0., -0.]],
[[0., -3.], [-3., 0.]],
[[0., -0.], [-0., -0.]],
[[-0., -0.], [-0., 0.]],
[[-0., 2.], [2., -0.]],
[[-0., 0.], [0., 0.]],
[[0., 0.], [0., -0.]],
[[0., 2.], [2., -0.]]])
assert(np.isclose(ref, w).all())
def test_regge_tet():
# Simplest element
regge = basix.create_element(basix.ElementFamily.Regge, basix.CellType.tetrahedron, 1)
# tabulate at origin
pts = [[0.0, 0.0, 0.0]]
w = regge.tabulate(0, pts)[0].reshape(-1, 3, 3)
ref = np.array([[[0., 0., 0.], [0., 0., 0.5], [0., 0.5, -0.]],
[[-0., 0., -0.], [0., -0., 0.5], [-0., 0.5, 0.]],
[[0., -0., 0.5], [-0., 0., 0.], [0.5, 0., 0.]],
[[-0., 0., 0.5], [0., -0., 0.], [0.5, 0., 0.]],
[[-0., 0.5, 0.], [0.5, -0., -0.], [0., -0., 0.]],
[[0., 0.5, 0.], [0.5, -0., 0.], [0., 0., 0.]],
[[0., 0., 1.], [0., 0., 1.], [1., 1., 2.]],
[[0., -0., -0.5], [-0., 0., -0.5], [-0.5, -0.5, -1.]],
[[0., 1., -0.], [1., 2., 1.], [-0., 1., -0.]],
[[-0., -0.5, -0.], [-0.5, -1., -0.5], [-0., -0.5, -0.]],
[[2., 1., 1.], [1., -0., 0.], [1., 0., 0.]],
[[-1., -0.5, -0.5], [-0.5, -0., 0.], [-0.5, 0., -0.]],
[[-0., 0., -0.], [0., -0., -0.], [-0., -0., -0.]],
[[-0., -0., -0.], [-0., -0., -0.], [-0., -0., -0.]],
[[-0., 0., -0.], [0., 0., -0.], [-0., -0., -0.]],
[[0., -0., 0.], [-0., -0., -0.], [0., -0., 0.]],
[[-0., -0., -0.], [-0., -0., 0.], [-0., 0., 0.]],
[[-0., -0., -0.], [-0., -0., -1.5], [-0., -1.5, -0.]],
[[0., -0., 0.], [-0., 0., -0.], [0., -0., 0.]],
[[0., -0., -0.], [-0., -0., -0.], [-0., -0., 0.]],
[[-0., 0., -1.5], [0., -0., -0.], [-1.5, -0., -0.]],
[[-0., -0., -0.], [-0., 0., -0.], [-0., -0., -0.]],
[[0., -0., -0.], [-0., -0., -0.], [-0., -0., 0.]],
[[-0., -1.5, -0.], [-1.5, 0., -0.], [-0., -0., -0.]]])
assert(np.isclose(ref, w).all())
def test_transformation_of_tabulated_data_quadrilateral(element_type, degree, element_args):
e = basix.create_element(element_type, basix.CellType.quadrilateral, degree, *element_args)
bt = e.base_transformations()
N = 4
points = np.array([[i / N, j / N] for i in range(N + 1) for j in range(N + 1)])
values = e.tabulate(0, points)[0]
start = sum(e.num_entity_dofs[0])
ndofs = e.num_entity_dofs[1][0]
if ndofs != 0:
# Check that the 0th transformation undoes the effect of reflecting edge 0
reflected_points = np.array([[1 - p[0], p[1]] for p in points])
reflected_values = e.tabulate(0, reflected_points)[0]
_J = np.array([[-1, 0], [0, 1]])
J = np.array([_J for p in points])
detJ = np.array([np.linalg.det(_J) for p in points])
K = np.array([np.linalg.inv(_J) for p in points])
mapped_values = e.push_forward(reflected_values, J, detJ, K)
for i, j in zip(values, mapped_values):
for d in range(e.value_size):
i_slice = i[:, d]
j_slice = j[:, d]
assert np.allclose((bt[0].dot(i_slice))[start: start + ndofs],
j_slice[start: start + ndofs])
def test_interpolation(cell_type, n, element_type):
element = basix.create_element(element_type, cell_type, n,
basix.LagrangeVariant.gll_warped)
assert element.interpolation_matrix.shape[0] == element.dim
assert element.interpolation_matrix.shape[1] == element.points.shape[0]
assert element.points.shape[1] == len(basix.topology(
element.cell_type)) - 1
def test_tet(order):
celltype = basix.CellType.tetrahedron
g = sympy_rt(celltype, order)
x = sympy.Symbol("x")
y = sympy.Symbol("y")
z = sympy.Symbol("z")
rt = basix.create_element(basix.ElementFamily.RT,
basix.CellType.tetrahedron, order)
pts = basix.create_lattice(celltype, 5, basix.LatticeType.equispaced, True)
nderiv = 1
wtab = rt.tabulate(nderiv, pts)
for kx in range(nderiv + 1):
for ky in range(nderiv + 1 - kx):
for kz in range(nderiv + 1 - kx - ky):
wsym = numpy.zeros_like(wtab[0])
for i, gi in enumerate(g):
for j, gij in enumerate(gi):
wd = sympy.diff(gij, x, kx, y, ky, z, kz)
for k, p in enumerate(pts):
wsym[k, i, j] = wd.subs([(x, p[0]), (y, p[1]),
(z, p[2])])
assert (numpy.isclose(wtab[basix.index(kx, ky, kz)],
wsym).all())
def test_dof_transformations_triangle(degree):
lagrange = basix.create_element(basix.ElementFamily.P,
basix.CellType.triangle, degree,
basix.LagrangeVariant.equispaced)
permuted = {}
if degree == 3:
# Reflect 2 DOFs on edges
permuted[0] = {3: 4, 4: 3}
permuted[1] = {5: 6, 6: 5}
permuted[2] = {7: 8, 8: 7}
elif degree == 4:
# Reflect 3 DOFs on edges
permuted[0] = {3: 5, 5: 3}
permuted[1] = {6: 8, 8: 6}
permuted[2] = {9: 11, 11: 9}
base_transformations = lagrange.base_transformations()
assert len(base_transformations) == 3
for i, t in enumerate(base_transformations):
actual = numpy.zeros_like(t)
for j, row in enumerate(t):
if i in permuted and j in permuted[i]:
actual[j, permuted[i][j]] = 1
else:
actual[j, j] = 1
assert numpy.allclose(t, actual)
def test_if_identity(cell_type, element_type, degree, element_args):
e = basix.create_element(element_type, cell_type, degree, *element_args)
for t in e.base_transformations():
if not np.allclose(t, np.eye(t.shape[0])):
assert not e.dof_transformations_are_identity
return
assert e.dof_transformations_are_identity
def test_mappings_2d_to_2d(element_type, element_args):
e = basix.create_element(element_type, basix.CellType.triangle, 1,
*element_args)
J = np.array([[random.random() + 1, random.random()],
[random.random(), random.random()]])
detJ = np.linalg.det(J)
K = np.linalg.inv(J)
run_map_test(e, J, detJ, K, e.value_size, e.value_size)
def __init__(self, family_type, cell_type, degree, variant_info,
discontinuous):
self.element = basix.create_element(family_type, cell_type, degree,
*variant_info, discontinuous)
self._family = family_type
self._cell = cell_type
self._variant_info = variant_info
self._discontinuous = discontinuous
def test_quadrilateral_transformation_degrees(element_type, degree, element_args):
e = basix.create_element(element_type, basix.CellType.quadrilateral, degree, *element_args)
bt = e.base_transformations()
assert len(bt) == 4
identity = np.identity(e.dim)
for i, degree in enumerate([2, 2, 2, 2]):
assert np.allclose(
np.linalg.matrix_power(bt[i], degree),
identity)
def test_if_permutations(cell_type, element_type, degree, element_args):
e = basix.create_element(element_type, cell_type, degree, *element_args)
for t in e.base_transformations():
for row in t:
a = np.argmax(row)
if not np.isclose(row[a], 1) or not np.allclose(row[:a], 0) or not np.allclose(row[a + 1:], 0):
assert not e.dof_transformations_are_permutations
return
assert e.dof_transformations_are_permutations
def test_dof_transformations_to_transpose(cell, element, degree, block_size,
element_args):
try:
import numba # noqa: F401
except ImportError:
pytest.skip("Numba must be installed to run this test.")
from basix import numba_helpers
from numba.core import types
from numba.typed import Dict
transform_functions = {
basix.CellType.triangle:
numba_helpers.apply_dof_transformation_to_transpose_triangle,
basix.CellType.quadrilateral:
numba_helpers.apply_dof_transformation_to_transpose_quadrilateral,
basix.CellType.tetrahedron:
numba_helpers.apply_dof_transformation_to_transpose_tetrahedron,
basix.CellType.hexahedron:
numba_helpers.apply_dof_transformation_to_transpose_hexahedron,
basix.CellType.prism:
numba_helpers.apply_dof_transformation_to_transpose_prism,
basix.CellType.pyramid:
numba_helpers.apply_dof_transformation_to_transpose_pyramid
}
random.seed(1337)
e = basix.create_element(element, cell, degree, *element_args)
data = np.array(list(range(e.dim * block_size)), dtype=np.double)
for i in range(10):
cell_info = random.randrange(2**30)
data1 = data.copy()
data1 = e.apply_dof_transformation_to_transpose(
data1, block_size, cell_info)
# Numba function does not use blocked data
data2 = data.copy().reshape(block_size, e.dim)
# Mapping lists to numba dictionaries
entity_transformations = Dict.empty(key_type=types.string,
value_type=types.float64[:, :, :])
for i, transformation in e.entity_transformations().items():
entity_transformations[i] = transformation
entity_dofs = Dict.empty(key_type=types.int64,
value_type=types.int32[:])
for i, e_dofs in enumerate(e.num_entity_dofs):
entity_dofs[i] = np.asarray(e_dofs, dtype=np.int32)
transform_functions[cell](entity_transformations, entity_dofs, data2,
cell_info)
# Reshape numba output for comparison
data2 = data2.reshape(-1)
assert np.allclose(data1, data2)
def test_number_of_dofs(cell_type, degree, element_type, element_args):
element = basix.create_element(element_type, cell_type, degree,
*element_args)
entity_dofs = element.entity_dofs
num_entity_dofs = element.num_entity_dofs
for entity_dofs, num_entity_dofs in zip(element.entity_dofs,
element.num_entity_dofs):
for dofs, ndofs in zip(entity_dofs, num_entity_dofs):
assert len(dofs) == ndofs
assert element.dim == sum(sum(i) for i in element.num_entity_dofs)
def test_tensor_product_factorisation_quadrilateral(degree):
P = degree
cell_type = basix.CellType.quadrilateral
element = basix.create_element(basix.ElementFamily.P, cell_type, P,
basix.LagrangeVariant.gll_warped)
factors = element.get_tensor_product_representation()[0]
# Quadrature degree
Q = 2 * P + 2
points, w = basix.make_quadrature(basix.QuadratureType.Default, cell_type,
Q)
data = element.tabulate(1, points)
dphi_x = data[1, :, :, 0]
dphi_y = data[2, :, :, 0]
assert points.shape[0] == (P + 2) * (P + 2)
# FIXME: This test assumes all factors formed by a single element
perm = factors[1]
element0 = factors[0][0]
cell1d = element0.cell_type
points, w = basix.make_quadrature(basix.QuadratureType.Default, cell1d, Q)
data = element0.tabulate(1, points)
phi0 = data[0, :, :, 0]
dphi0 = data[1, :, :, 0]
# number of dofs in each direction
Nd = P + 1
# number of quadrature points in each direction
Nq = P + 2
# Compute derivative of basis function in the x direction
dphi_tensor = numpy.zeros([Nq, Nq, Nd, Nd])
for q0 in range(Nq):
for q1 in range(Nq):
for i0 in range(Nd):
for i1 in range(Nd):
dphi_tensor[q0, q1, i0, i1] = dphi0[q0, i0] * phi0[q1, i1]
dphi_tensor = dphi_tensor.reshape([Nq * Nq, Nd * Nd])
assert numpy.allclose(dphi_x[:, perm], dphi_tensor)
# Compute derivative of basis function in the y direction
dphi_tensor = numpy.zeros([Nq, Nq, Nd, Nd])
for q0 in range(Nq):
for q1 in range(Nq):
for i0 in range(Nd):
for i1 in range(Nd):
dphi_tensor[q0, q1, i0, i1] = phi0[q0, i0] * dphi0[q1, i1]
dphi_tensor = dphi_tensor.reshape([Nq * Nq, Nd * Nd])
assert numpy.allclose(dphi_y[:, perm], dphi_tensor)
def test_mappings_2d_to_3d(element_type, element_args):
e = basix.create_element(element_type, basix.CellType.triangle, 1,
*element_args)
# Map from (0,0)--(1,0)--(0,1) to (1,0,1)--(2,1,0)--(0,1,1)
J = np.array([[1., -1.], [1., 1.], [-1., 0.]])
detJ = np.sqrt(6)
K = np.array([[0.5, 0.5, 0.], [-0.5, 0.5, 0.]])
if e.value_size == 1:
physical_vs = 1
elif e.value_size == 2:
physical_vs = 3
elif e.value_size == 4:
physical_vs = 9
run_map_test(e, J, detJ, K, e.value_size, physical_vs)
def test_closure_dofs(cell_type, degree, element_type, element_args):
element = basix.create_element(element_type, cell_type, degree,
*element_args)
entity_dofs = element.entity_dofs
entity_closure_dofs = element.entity_closure_dofs
topology = basix.topology(cell_type)
connectivity = basix.cell.sub_entity_connectivity(cell_type)
for dim, t in enumerate(topology):
for e, _ in enumerate(t):
for dim2 in range(dim + 1):
for e2 in connectivity[dim][e][dim2]:
for dof in entity_dofs[dim2][e2]:
assert dof in entity_closure_dofs[dim][e]
def test_line_without_variant(n):
celltype = basix.CellType.interval
g = sympy_lagrange(celltype, n)
x = sympy.Symbol("x")
lagrange = basix.create_element(basix.ElementFamily.P,
basix.CellType.interval, n)
pts = basix.create_lattice(celltype, 6, basix.LatticeType.equispaced, True)
nderiv = n
wtab = lagrange.tabulate(nderiv, pts)
for k in range(nderiv + 1):
wsym = numpy.zeros_like(wtab[k])
for i in range(n + 1):
wd = sympy.diff(g[i], x, k)
for j, p in enumerate(pts):
wsym[j, i] = wd.subs(x, p[0])
assert numpy.allclose(wtab[k], wsym)
def test_ordering_of_dofs(cell_type, degree, element_type, element_args):
"""
Check that DOFs are numbered in ascending order by entity.
This assumption is required for DOF transformations to work correctly.
"""
element = basix.create_element(element_type, cell_type, degree,
*element_args)
entity_dofs = element.entity_dofs
dof = 0
print(element.entity_dofs)
for entity_dofs in element.entity_dofs:
for dofs in entity_dofs:
for d in sorted(dofs):
assert d == dof
dof += 1
def test_regge_tri():
# Simplest element
regge = basix.create_element(basix.ElementFamily.Regge, basix.CellType.triangle, 1)
# tabulate at origin
pts = [[0.0, 0.0]]
w = regge.tabulate(0, pts)[0].reshape(-1, 2, 2)
ref = np.array([[[-0., 0.5], [0.5, -0.]],
[[0., 0.5], [0.5, -0.]],
[[-0., 1.], [1., 2.]],
[[-0., -0.5], [-0.5, -1.]],
[[2., 1.], [1., -0.]],
[[-1., -0.5], [-0.5, 0.]],
[[-0., 0.], [0., 0.]],
[[0., -0.], [-0., -0.]],
[[-0., -1.5], [-1.5, 0.]]])
assert np.allclose(ref, w)
def test_dof_transformations_tetrahedron(degree):
lagrange = basix.create_element(basix.ElementFamily.P,
basix.CellType.tetrahedron, degree,
basix.LagrangeVariant.equispaced)
permuted = {}
if degree == 3:
# Reflect 2 DOFs on edges
permuted[0] = {4: 5, 5: 4}
permuted[1] = {6: 7, 7: 6}
permuted[2] = {8: 9, 9: 8}
permuted[3] = {10: 11, 11: 10}
permuted[4] = {12: 13, 13: 12}
permuted[5] = {14: 15, 15: 14}
elif degree == 4:
# Reflect 3 DOFs on edges
permuted[0] = {4: 6, 6: 4}
permuted[1] = {7: 9, 9: 7}
permuted[2] = {10: 12, 12: 10}
permuted[3] = {13: 15, 15: 13}
permuted[4] = {16: 18, 18: 16}
permuted[5] = {19: 21, 21: 19}
# Rotate and reflect 3 DOFs on faces
permuted[6] = {22: 24, 23: 22, 24: 23}
permuted[7] = {23: 24, 24: 23}
permuted[8] = {25: 27, 26: 25, 27: 26}
permuted[9] = {26: 27, 27: 26}
permuted[10] = {28: 30, 29: 28, 30: 29}
permuted[11] = {29: 30, 30: 29}
permuted[12] = {31: 33, 32: 31, 33: 32}
permuted[13] = {32: 33, 33: 32}
base_transformations = lagrange.base_transformations()
assert len(base_transformations) == 14
for i, t in enumerate(base_transformations):
actual = numpy.zeros_like(t)
for j, row in enumerate(t):
if i in permuted and j in permuted[i]:
actual[j, permuted[i][j]] = 1
else:
actual[j, j] = 1
assert numpy.allclose(t, actual)
def test_tensor_product_factorisation(cell_type, degree, element_type,
element_args):
element = basix.create_element(element_type, cell_type, degree,
*element_args)
tdim = len(basix.topology(cell_type)) - 1
# These elements should have a factorisation
if cell_type in [basix.CellType.quadrilateral,
basix.CellType.hexahedron] and element_type in [
basix.ElementFamily.P
] and basix.LagrangeVariant.equispaced in element_args:
assert element.has_tensor_product_factorisation
if not element.has_tensor_product_factorisation:
with pytest.raises(RuntimeError):
element.get_tensor_product_representation()
pytest.skip()
factors = element.get_tensor_product_representation()
lattice = basix.create_lattice(cell_type, 1, basix.LatticeType.equispaced,
True)
tab1 = element.tabulate(1, lattice)
for i, point in enumerate(lattice):
for ds in product(range(2), repeat=tdim):
if sum(ds) > 1:
continue
deriv = basix.index(*ds)
values1 = tab1[deriv, i, :, :]
values2 = np.empty((element.dim, 1))
for fs, perm in factors:
evals = [
e.tabulate(d, [p])[d, 0, :, 0]
for e, p, d in zip(fs, point, ds)
]
tab2 = tensor_product(*evals)
for a, b in enumerate(perm):
if b != -1:
values2[b, 0] = tab2[a]
assert np.allclose(values1, values2)
def test_tri(order):
celltype = basix.CellType.triangle
g = sympy_nedelec(celltype, order)
x = sympy.Symbol("x")
y = sympy.Symbol("y")
nedelec = basix.create_element(basix.ElementFamily.N1E, basix.CellType.triangle, order)
pts = basix.create_lattice(celltype, 6, basix.LatticeType.equispaced, True)
nderiv = 3
wtab = nedelec.tabulate(nderiv, pts)
for kx in range(nderiv + 1):
for ky in range(nderiv + 1 - kx):
wsym = numpy.zeros_like(wtab[0])
for i, gi in enumerate(g):
for j, gij in enumerate(gi):
wd = sympy.diff(gij, x, kx, y, ky)
for k, p in enumerate(pts):
wsym[k, i, j] = wd.subs([(x, p[0]), (y, p[1])])
assert(numpy.isclose(wtab[basix.index(kx, ky)], wsym).all())
