def test_tensor_element():
L = TensorIndexType("L")
i, j, k, l, m, n = tensor_indices("i j k l m n", L)
A = TensorHead("A", [L, L], TensorSymmetry.no_symmetry(2))
a = A(i, j)
assert isinstance(TensorElement(a, {}), Tensor)
assert isinstance(TensorElement(a, {k: 1}), Tensor)
te1 = TensorElement(a, {Symbol("i"): 1})
assert te1.free == [(j, 0)]
assert te1.get_free_indices() == [j]
assert te1.dum == []
te2 = TensorElement(a, {i: 1})
assert te2.free == [(j, 0)]
assert te2.get_free_indices() == [j]
assert te2.dum == []
assert te1 == te2
array = Array([[1, 2], [3, 4]])
assert te1.replace_with_arrays({A(i, j): array}, [j]) == array[1, :]
def test_gamma_matrix_class():
i, j, k = tensor_indices("i,j,k", LorentzIndex)
# define another type of TensorHead to see if exprs are correctly handled:
A = TensorHead("A", [LorentzIndex])
t = A(k) * G(i) * G(-i)
ts = simplify_gamma_expression(t)
assert _is_tensor_eq(
ts, Matrix([[4, 0, 0, 0], [0, 4, 0, 0], [0, 0, 4, 0], [0, 0, 0, 4]]) * A(k)
)
t = G(i) * A(k) * G(j)
ts = simplify_gamma_expression(t)
assert _is_tensor_eq(ts, A(k) * G(i) * G(j))
execute_gamma_simplify_tests_for_function(simplify_gamma_expression, D=4)
from sympy.tensor.toperators import PartialDerivative
from sympy.tensor.tensor import (TensorIndexType, tensor_indices, TensorHead,
tensor_heads)
from sympy import symbols, diag
from sympy import Array, Rational
from random import randint
L = TensorIndexType("L")
i, j, k, m, m1, m2, m3, m4 = tensor_indices("i j k m m1 m2 m3 m4", L)
i0 = tensor_indices("i0", L)
L_0, L_1 = tensor_indices("L_0 L_1", L)
A, B, C, D = tensor_heads("A B C D", [L])
H = TensorHead("H", [L, L])
def test_invalid_partial_derivative_valence():
raises(ValueError, lambda: PartialDerivative(C(j), D(-j)))
raises(ValueError, lambda: PartialDerivative(C(-j), D(j)))
def test_tensor_partial_deriv():
# Test flatten:
expr = PartialDerivative(PartialDerivative(A(i), A(j)), A(i))
assert expr.expr == A(L_0)
assert expr.variables == (A(j), A(L_0))
expr1 = PartialDerivative(A(i), A(j))
assert expr1.expr == A(i)
metric(LorentzIndex,LorentzIndex)
"""
from sympy.core.mul import Mul
from sympy.core.singleton import S
from sympy.matrices.dense import eye
from sympy.matrices.expressions.trace import trace
from sympy.tensor.tensor import TensorIndexType, TensorIndex,\
TensMul, TensAdd, tensor_mul, Tensor, TensorHead, TensorSymmetry
# DiracSpinorIndex = TensorIndexType('DiracSpinorIndex', dim=4, dummy_name="S")
LorentzIndex = TensorIndexType('LorentzIndex', dim=4, dummy_name="L")
GammaMatrix = TensorHead("GammaMatrix", [LorentzIndex],
TensorSymmetry.no_symmetry(1),
comm=None)
def extract_type_tens(expression, component):
"""
Extract from a ``TensExpr`` all tensors with `component`.
Returns two tensor expressions:
* the first contains all ``Tensor`` of having `component`.
* the second contains all remaining.
"""
if isinstance(expression, Tensor):
