def test_matrix_expressions():
n = symbols('n', integer=True)
A = MatrixSymbol("A", n, n)
B = MatrixSymbol("B", n, n)
sT(A, "MatrixSymbol(Str('A'), Symbol('n', integer=True), Symbol('n', integer=True))")
sT(A*B, "MatMul(MatrixSymbol(Str('A'), Symbol('n', integer=True), Symbol('n', integer=True)), MatrixSymbol(Str('B'), Symbol('n', integer=True), Symbol('n', integer=True)))")
sT(A + B, "MatAdd(MatrixSymbol(Str('A'), Symbol('n', integer=True), Symbol('n', integer=True)), MatrixSymbol(Str('B'), Symbol('n', integer=True), Symbol('n', integer=True)))")
def test_arrayexpr_array_expr_zero_array():
za1 = ZeroArray(k, l, m, n)
zm1 = ZeroMatrix(m, n)
za2 = ZeroArray(k, m, m, n)
zm2 = ZeroMatrix(m, m)
zm3 = ZeroMatrix(k, k)
assert _array_tensor_product(M, N, za1) == ZeroArray(k, k, k, k, k, l, m, n)
assert _array_tensor_product(M, N, zm1) == ZeroArray(k, k, k, k, m, n)
assert _array_contraction(za1, (3,)) == ZeroArray(k, l, m)
assert _array_contraction(zm1, (1,)) == ZeroArray(m)
assert _array_contraction(za2, (1, 2)) == ZeroArray(k, n)
assert _array_contraction(zm2, (0, 1)) == 0
assert _array_diagonal(za2, (1, 2)) == ZeroArray(k, n, m)
assert _array_diagonal(zm2, (0, 1)) == ZeroArray(m)
assert _permute_dims(za1, [2, 1, 3, 0]) == ZeroArray(m, l, n, k)
assert _permute_dims(zm1, [1, 0]) == ZeroArray(n, m)
assert _array_add(za1) == za1
assert _array_add(zm1) == ZeroArray(m, n)
tp1 = _array_tensor_product(MatrixSymbol("A", k, l), MatrixSymbol("B", m, n))
assert _array_add(tp1, za1) == tp1
tp2 = _array_tensor_product(MatrixSymbol("C", k, l), MatrixSymbol("D", m, n))
assert _array_add(tp1, za1, tp2) == _array_add(tp1, tp2)
assert _array_add(M, zm3) == M
assert _array_add(M, N, zm3) == _array_add(M, N)
def test_MatrixSlice():
n = Symbol('n', integer=True)
X = MatrixSymbol('X', n, n)
Y = MatrixSymbol('Y', 10, 10)
Z = MatrixSymbol('Z', 10, 10)
assert str(MatrixSlice(X, (None, None, None), (None, None, None))) == 'X[:, :]'
assert str(X[x:x + 1, y:y + 1]) == 'X[x:x + 1, y:y + 1]'
assert str(X[x:x + 1:2, y:y + 1:2]) == 'X[x:x + 1:2, y:y + 1:2]'
assert str(X[:x, y:]) == 'X[:x, y:]'
assert str(X[:x, y:]) == 'X[:x, y:]'
assert str(X[x:, :y]) == 'X[x:, :y]'
assert str(X[x:y, z:w]) == 'X[x:y, z:w]'
assert str(X[x:y:t, w:t:x]) == 'X[x:y:t, w:t:x]'
assert str(X[x::y, t::w]) == 'X[x::y, t::w]'
assert str(X[:x:y, :t:w]) == 'X[:x:y, :t:w]'
assert str(X[::x, ::y]) == 'X[::x, ::y]'
assert str(MatrixSlice(X, (0, None, None), (0, None, None))) == 'X[:, :]'
assert str(MatrixSlice(X, (None, n, None), (None, n, None))) == 'X[:, :]'
assert str(MatrixSlice(X, (0, n, None), (0, n, None))) == 'X[:, :]'
assert str(MatrixSlice(X, (0, n, 2), (0, n, 2))) == 'X[::2, ::2]'
assert str(X[1:2:3, 4:5:6]) == 'X[1:2:3, 4:5:6]'
assert str(X[1:3:5, 4:6:8]) == 'X[1:3:5, 4:6:8]'
assert str(X[1:10:2]) == 'X[1:10:2, :]'
assert str(Y[:5, 1:9:2]) == 'Y[:5, 1:9:2]'
assert str(Y[:5, 1:10:2]) == 'Y[:5, 1::2]'
assert str(Y[5, :5:2]) == 'Y[5:6, :5:2]'
assert str(X[0:1, 0:1]) == 'X[:1, :1]'
assert str(X[0:1:2, 0:1:2]) == 'X[:1:2, :1:2]'
assert str((Y + Z)[2:, 2:]) == '(Y + Z)[2:, 2:]'
def test_MatrixPermute_doit():
p = Permutation(0, 1, 2)
A = MatrixSymbol('A', 3, 3)
assert MatrixPermute(A, p).doit() == MatrixPermute(A, p)
p = Permutation(0, size=3)
A = MatrixSymbol('A', 3, 3)
assert MatrixPermute(A, p).doit().as_explicit() == \
MatrixPermute(A, p).as_explicit()
p = Permutation(0, 1, 2)
A = Identity(3)
assert MatrixPermute(A, p, 0).doit().as_explicit() == \
MatrixPermute(A, p, 0).as_explicit()
assert MatrixPermute(A, p, 1).doit().as_explicit() == \
MatrixPermute(A, p, 1).as_explicit()
A = ZeroMatrix(3, 3)
assert MatrixPermute(A, p).doit() == A
A = OneMatrix(3, 3)
assert MatrixPermute(A, p).doit() == A
A = MatrixSymbol('A', 4, 4)
p1 = Permutation(0, 1, 2, 3)
p2 = Permutation(0, 2, 3, 1)
expr = MatrixPermute(MatrixPermute(A, p1, 0), p2, 0)
assert expr.as_explicit() == expr.doit().as_explicit()
expr = MatrixPermute(MatrixPermute(A, p1, 1), p2, 1)
assert expr.as_explicit() == expr.doit().as_explicit()
def test_matrix():
from sympy.matrices.expressions.matexpr import MatrixSymbol
X = MatrixSymbol('X', n, n)
Y = MatrixSymbol('Y', 2, 2)
Z = MatrixSymbol('Z', 2, 3)
assert list(unify(X, Y, {}, variables=[n, Str('X')])) == [{Str('X'): Str('Y'), n: 2}]
assert list(unify(X, Z, {}, variables=[n, Str('X')])) == []
def test_OneMatrix():
n, m = symbols('n m', integer=True)
A = MatrixSymbol('A', n, m)
a = MatrixSymbol('a', n, 1)
U = OneMatrix(n, m)
assert U.shape == (n, m)
assert isinstance(A + U, Add)
assert U.transpose() == OneMatrix(m, n)
assert U.conjugate() == U
assert OneMatrix(n, n)**0 == Identity(n)
with raises(NonSquareMatrixError):
U**0
with raises(NonSquareMatrixError):
U**1
with raises(NonSquareMatrixError):
U**2
with raises(ShapeError):
a + U
U = OneMatrix(n, n)
assert U[1, 2] == 1
U = OneMatrix(2, 3)
assert U.as_explicit() == ImmutableDenseMatrix.ones(2, 3)
def test_MatrixSet():
n, m = symbols('n m', integer=True)
A = MatrixSymbol('A', n, m)
C = MatrixSymbol('C', n, n)
M = MatrixSet(2, 2, set=S.Reals)
assert M.shape == (2, 2)
assert M.set == S.Reals
X = Matrix([[1, 2], [3, 4]])
assert X in M
X = ZeroMatrix(2, 2)
assert X in M
raises(TypeError, lambda: A in M)
raises(TypeError, lambda: 1 in M)
M = MatrixSet(n, m, set=S.Reals)
assert A in M
raises(TypeError, lambda: C in M)
raises(TypeError, lambda: X in M)
M = MatrixSet(2, 2, set={1, 2, 3})
X = Matrix([[1, 2], [3, 4]])
Y = Matrix([[1, 2]])
assert (X in M) == S.false
assert (Y in M) == S.false
raises(ValueError, lambda: MatrixSet(2, -2, S.Reals))
raises(ValueError, lambda: MatrixSet(2.4, -1, S.Reals))
raises(TypeError, lambda: MatrixSet(2, 2, (1, 2, 3)))
def test_MatrixPermute_explicit():
p = Permutation(0, 1, 2)
A = MatrixSymbol('A', 3, 3)
AA = A.as_explicit()
assert MatrixPermute(A, p, 0).as_explicit() == \
AA.permute(p, orientation='rows')
assert MatrixPermute(A, p, 1).as_explicit() == \
AA.permute(p, orientation='cols')
def test_MatMul_MatAdd():
X, Y = MatrixSymbol("X", 2, 2), MatrixSymbol("Y", 2, 2)
assert str(2*(X + Y)) == "2*X + 2*Y"
assert str(I*X) == "I*X"
assert str(-I*X) == "-I*X"
assert str((1 + I)*X) == '(1 + I)*X'
assert str(-(1 + I)*X) == '(-1 - I)*X'
def test_block_index_symbolic_fail():
# To make this work, symbolic matrix dimensions would need to be somehow assumed nonnegative
# even if the symbols aren't specified as such. Then 2 * n < n would correctly evaluate to
# False in BlockMatrix._entry()
A1 = MatrixSymbol('A1', n, 1)
A2 = MatrixSymbol('A2', m, 1)
A = BlockMatrix([[A1], [A2]])
assert A[2 * n, 0] == A2[n, 0]
def test_MatrixSymbol_printing():
A = MatrixSymbol("A", 3, 3)
B = MatrixSymbol("B", 3, 3)
assert str(A - A*B - B) == "A - A*B - B"
assert str(A*B - (A+B)) == "-A + A*B - B"
assert str(A**(-1)) == "A**(-1)"
assert str(A**3) == "A**3"
def test_matsolve():
n = Symbol('n', integer=True)
A = MatrixSymbol('A', n, n)
x = MatrixSymbol('x', n, 1)
with assuming(Q.fullrank(A)):
assert optimize(A**(-1) * x, [matinv_opt]) == MatrixSolve(A, x)
assert optimize(A**(-1) * x + x, [matinv_opt]) == MatrixSolve(A, x) + x
def test_MatrixPermute_explicit():
p = Permutation(0, 1, 2)
A = MatrixSymbol("A", 3, 3)
AA = A.as_explicit()
assert MatrixPermute(A, p,
0).as_explicit() == AA.permute(p, orientation="rows")
assert MatrixPermute(A, p,
1).as_explicit() == AA.permute(p, orientation="cols")
def test_arrayexpr_convert_array_to_matrix():
cg = _array_contraction(_array_tensor_product(M), (0, 1))
assert convert_array_to_matrix(cg) == Trace(M)
cg = _array_contraction(_array_tensor_product(M, N), (0, 1), (2, 3))
assert convert_array_to_matrix(cg) == Trace(M) * Trace(N)
cg = _array_contraction(_array_tensor_product(M, N), (0, 3), (1, 2))
assert convert_array_to_matrix(cg) == Trace(M * N)
cg = _array_contraction(_array_tensor_product(M, N), (0, 2), (1, 3))
assert convert_array_to_matrix(cg) == Trace(M * N.T)
cg = convert_matrix_to_array(M * N * P)
assert convert_array_to_matrix(cg) == M * N * P
cg = convert_matrix_to_array(M * N.T * P)
assert convert_array_to_matrix(cg) == M * N.T * P
cg = _array_contraction(_array_tensor_product(M,N,P,Q), (1, 2), (5, 6))
assert convert_array_to_matrix(cg) == _array_tensor_product(M * N, P * Q)
cg = _array_contraction(_array_tensor_product(-2, M, N), (1, 2))
assert convert_array_to_matrix(cg) == -2 * M * N
a = MatrixSymbol("a", k, 1)
b = MatrixSymbol("b", k, 1)
c = MatrixSymbol("c", k, 1)
cg = PermuteDims(
_array_contraction(
_array_tensor_product(
a,
ArrayAdd(
_array_tensor_product(b, c),
_array_tensor_product(c, b),
)
), (2, 4)), [0, 1, 3, 2])
assert convert_array_to_matrix(cg) == a * (b.T * c + c.T * b)
za = ZeroArray(m, n)
assert convert_array_to_matrix(za) == ZeroMatrix(m, n)
cg = _array_tensor_product(3, M)
assert convert_array_to_matrix(cg) == 3 * M
# Partial conversion to matrix multiplication:
expr = _array_contraction(_array_tensor_product(M, N, P, Q), (0, 2), (1, 4, 6))
assert convert_array_to_matrix(expr) == _array_contraction(_array_tensor_product(M.T*N, P, Q), (0, 2, 4))
x = MatrixSymbol("x", k, 1)
cg = PermuteDims(
_array_contraction(_array_tensor_product(OneArray(1), x, OneArray(1), DiagMatrix(Identity(1))),
(0, 5)), Permutation(1, 2, 3))
assert convert_array_to_matrix(cg) == x
expr = ArrayAdd(M, PermuteDims(M, [1, 0]))
assert convert_array_to_matrix(expr) == M + Transpose(M)
def test_dotproduct_symbolic():
A = MatrixSymbol('A', 3, 1)
B = MatrixSymbol('B', 3, 1)
dot = DotProduct(A, B)
assert dot.is_scalar == True
assert unchanged(Mul, 2, dot)
# XXX Fix forced evaluation for arithmetics with matrix expressions
assert dot * A == (A[0, 0]*B[0, 0] + A[1, 0]*B[1, 0] + A[2, 0]*B[2, 0])*A
def test_mul_index():
assert (A*y)[0, 0] == A[0, 0]*y[0, 0] + A[0, 1]*y[1, 0]
assert (A*B).as_mutable() == (A.as_mutable() * B.as_mutable())
X = MatrixSymbol('X', n, m)
Y = MatrixSymbol('Y', m, k)
result = (X*Y)[4,2]
expected = Sum(X[4, i]*Y[i, 2], (i, 0, m - 1))
assert result.args[0].dummy_eq(expected.args[0], i)
assert result.args[1][1:] == expected.args[1][1:]
def test_applyfunc_shape_11_matrices():
M = MatrixSymbol("M", 1, 1)
double = Lambda(x, x * 2)
expr = M.applyfunc(sin)
assert isinstance(expr, ElementwiseApplyFunction)
expr = M.applyfunc(double)
assert isinstance(expr, MatMul)
assert expr == 2 * M
def test_MatrixElement_printing():
# test cases for issue #11821
A = MatrixSymbol("A", 1, 3)
B = MatrixSymbol("B", 1, 3)
C = MatrixSymbol("C", 1, 3)
assert(str(A[0, 0]) == "A[0, 0]")
assert(str(3 * A[0, 0]) == "3*A[0, 0]")
F = C[0, 0].subs(C, A - B)
assert str(F) == "(A - B)[0, 0]"
def test_issue_15601():
if not np:
skip("Numpy not installed")
M = MatrixSymbol("M", 3, 3)
N = MatrixSymbol("N", 3, 3)
expr = M * N
f = lambdify((M, N), expr, "numpy")
with warns_deprecated_sympy():
ans = f(eye(3), eye(3))
assert np.array_equal(ans, np.array([1, 0, 0, 0, 1, 0, 0, 0, 1]))
def test_16857():
if not np:
skip("NumPy not installed")
a_1 = MatrixSymbol('a_1', 10, 3)
a_2 = MatrixSymbol('a_2', 10, 3)
a_3 = MatrixSymbol('a_3', 10, 3)
a_4 = MatrixSymbol('a_4', 10, 3)
A = BlockMatrix([[a_1, a_2], [a_3, a_4]])
assert A.shape == (20, 6)
printer = NumPyPrinter()
assert printer.doprint(A) == 'numpy.block([[a_1, a_2], [a_3, a_4]])'
def test_codegen_einsum():
if not np:
skip("NumPy not installed")
M = MatrixSymbol("M", 2, 2)
N = MatrixSymbol("N", 2, 2)
cg = convert_matrix_to_array(M * N)
f = lambdify((M, N), cg, 'numpy')
ma = np.matrix([[1, 2], [3, 4]])
mb = np.matrix([[1, -2], [-1, 3]])
assert (f(ma, mb) == ma * mb).all()
def test_issue_9324():
def count(val):
return count_ops(val, visual=False)
M = MatrixSymbol('M', 10, 10)
assert count(M[0, 0]) == 0
assert count(2 * M[0, 0] + M[5, 7]) == 2
P = MatrixSymbol('P', 3, 3)
Q = MatrixSymbol('Q', 3, 3)
assert count(P + Q) == 1
m = Symbol('m', integer=True)
n = Symbol('n', integer=True)
M = MatrixSymbol('M', m + n, m * m)
assert count(M[0, 1]) == 2
def doprint(self, expr, assign_to=None):
"""
Print the expression as code.
Parameters
----------
expr : Expression
The expression to be printed.
assign_to : Symbol, MatrixSymbol, or string (optional)
If provided, the printed code will set the expression to a
variable with name ``assign_to``.
"""
from sympy.matrices.expressions.matexpr import MatrixSymbol
if isinstance(assign_to, string_types):
if expr.is_Matrix:
assign_to = MatrixSymbol(assign_to, *expr.shape)
else:
assign_to = Symbol(assign_to)
elif not isinstance(assign_to, (Basic, type(None))):
raise TypeError("{0} cannot assign to object of type {1}".format(
type(self).__name__, type(assign_to)))
if assign_to:
expr = Assignment(assign_to, expr)
else:
# _sympify is not enough b/c it errors on iterables
expr = sympify(expr)
# keep a set of expressions that are not strictly translatable to Code
# and number constants that must be declared and initialized
self._not_supported = set()
self._number_symbols = set()
if isinstance(expr, Eq):
expr = Assignment(expr.lhs, expr.rhs)
lines = self._print(expr).splitlines()
# format the output
if self._settings["human"]:
frontlines = []
if len(self._not_supported) > 0:
frontlines.append(self._get_comment(
"Not supported in {0}:".format(self.language)))
for expr in sorted(self._not_supported, key=str):
frontlines.append(self._get_comment(type(expr).__name__))
for name, value in sorted(self._number_symbols, key=str):
frontlines.append(self._declare_number_const(name, value))
lines = frontlines + lines
lines = self._format_code(lines)
result = "\n".join(lines)
else:
lines = self._format_code(lines)
result = (self._number_symbols, self._not_supported,
"\n".join(lines))
#del self._not_supported
#del self._number_symbols
return result
def test_Identity():
n, m = symbols('n m', integer=True)
A = MatrixSymbol('A', n, m)
i, j = symbols('i j')
In = Identity(n)
Im = Identity(m)
assert A * Im == A
assert In * A == A
assert In.transpose() == In
assert In.inverse() == In
assert In.conjugate() == In
assert In[i, j] != 0
assert Sum(In[i, j], (i, 0, n - 1), (j, 0, n - 1)).subs(n, 3).doit() == 3
assert Sum(Sum(In[i, j], (i, 0, n - 1)), (j, 0, n - 1)).subs(n,
3).doit() == 3
# If range exceeds the limit `(0, n-1)`, do not remove `Piecewise`:
expr = Sum(In[i, j], (i, 0, n - 1))
assert expr.doit() == 1
expr = Sum(In[i, j], (i, 0, n - 2))
assert expr.doit().dummy_eq(
Piecewise((1, (j >= 0) & (j <= n - 2)), (0, True)))
expr = Sum(In[i, j], (i, 1, n - 1))
assert expr.doit().dummy_eq(
Piecewise((1, (j >= 1) & (j <= n - 1)), (0, True)))
assert Identity(3).as_explicit() == ImmutableDenseMatrix.eye(3)
def test_issue_17006():
if not np:
skip("NumPy not installed")
M = MatrixSymbol("M", 2, 2)
f = lambdify(M, M + Identity(2))
ma = np.array([[1, 2], [3, 4]])
mr = np.array([[2, 2], [3, 5]])
assert (f(ma) == mr).all()
from sympy.core.symbol import symbols
n = symbols('n', integer=True)
N = MatrixSymbol("M", n, n)
raises(NotImplementedError, lambda: lambdify(N, N + Identity(n)))
def test_array_expr_reshape():
A = MatrixSymbol("A", 2, 2)
B = ArraySymbol("B", (2, 2, 2))
C = Array([1, 2, 3, 4])
expr = Reshape(A, (4,))
assert expr.expr == A
assert expr.shape == (4,)
assert expr.as_explicit() == Array([A[0, 0], A[0, 1], A[1, 0], A[1, 1]])
expr = Reshape(B, (2, 4))
assert expr.expr == B
assert expr.shape == (2, 4)
ee = expr.as_explicit()
assert isinstance(ee, ImmutableDenseNDimArray)
assert ee.shape == (2, 4)
assert ee == Array([[B[0, 0, 0], B[0, 0, 1], B[0, 1, 0], B[0, 1, 1]], [B[1, 0, 0], B[1, 0, 1], B[1, 1, 0], B[1, 1, 1]]])
expr = Reshape(A, (k, 2))
assert expr.shape == (k, 2)
raises(ValueError, lambda: Reshape(A, (2, 3)))
raises(ValueError, lambda: Reshape(A, (3,)))
expr = Reshape(C, (2, 2))
assert expr.expr == C
assert expr.shape == (2, 2)
assert expr.doit() == Array([[1, 2], [3, 4]])
def test_CondSet():
sin_sols_principal = ConditionSet(x, Eq(sin(x), 0),
Interval(0, 2*pi, False, True))
assert pi in sin_sols_principal
assert pi/2 not in sin_sols_principal
assert 3*pi not in sin_sols_principal
assert oo not in sin_sols_principal
assert 5 in ConditionSet(x, x**2 > 4, S.Reals)
assert 1 not in ConditionSet(x, x**2 > 4, S.Reals)
# in this case, 0 is not part of the base set so
# it can't be in any subset selected by the condition
assert 0 not in ConditionSet(x, y > 5, Interval(1, 7))
# since 'in' requires a true/false, the following raises
# an error because the given value provides no information
# for the condition to evaluate (since the condition does
# not depend on the dummy symbol): the result is `y > 5`.
# In this case, ConditionSet is just acting like
# Piecewise((Interval(1, 7), y > 5), (S.EmptySet, True)).
raises(TypeError, lambda: 6 in ConditionSet(x, y > 5,
Interval(1, 7)))
X = MatrixSymbol('X', 2, 2)
matrix_set = ConditionSet(X, Eq(X*Matrix([[1, 1], [1, 1]]), X))
Y = Matrix([[0, 0], [0, 0]])
assert matrix_set.contains(Y).doit() is S.true
Z = Matrix([[1, 2], [3, 4]])
assert matrix_set.contains(Z).doit() is S.false
assert isinstance(ConditionSet(x, x < 1, {x, y}).base_set,
FiniteSet)
raises(TypeError, lambda: ConditionSet(x, x + 1, {x, y}))
raises(TypeError, lambda: ConditionSet(x, x, 1))
I = S.Integers
U = S.UniversalSet
C = ConditionSet
assert C(x, False, I) is S.EmptySet
assert C(x, True, I) is I
assert C(x, x < 1, C(x, x < 2, I)
) == C(x, (x < 1) & (x < 2), I)
assert C(y, y < 1, C(x, y < 2, I)
) == C(x, (x < 1) & (y < 2), I), C(y, y < 1, C(x, y < 2, I))
assert C(y, y < 1, C(x, x < 2, I)
) == C(y, (y < 1) & (y < 2), I)
assert C(y, y < 1, C(x, y < x, I)
) == C(x, (x < 1) & (y < x), I)
assert unchanged(C, y, x < 1, C(x, y < x, I))
assert ConditionSet(x, x < 1).base_set is U
# arg checking is not done at instantiation but this
# will raise an error when containment is tested
assert ConditionSet((x,), x < 1).base_set is U
c = ConditionSet((x, y), x < y, I**2)
assert (1, 2) in c
assert (1, pi) not in c
raises(TypeError, lambda: C(x, x > 1, C((x, y), x > 1, I**2)))
# signature mismatch since only 3 args are accepted
raises(TypeError, lambda: C((x, y), x + y < 2, U, U))
def test_matrixelement():
x = MatrixSymbol('x', 3, 3)
i = Symbol('i', positive = True)
j = Symbol('j', positive = True)
assert refine(x[0, 1], Q.symmetric(x)) == x[0, 1]
assert refine(x[1, 0], Q.symmetric(x)) == x[0, 1]
assert refine(x[i, j], Q.symmetric(x)) == x[j, i]
assert refine(x[j, i], Q.symmetric(x)) == x[j, i]
def test_MatrixPermute_rewrite_MatMul():
p = Permutation(0, 1, 2)
A = MatrixSymbol('A', 3, 3)
assert MatrixPermute(A, p, 0).rewrite(MatMul).as_explicit() == \
MatrixPermute(A, p, 0).as_explicit()
assert MatrixPermute(A, p, 1).rewrite(MatMul).as_explicit() == \
MatrixPermute(A, p, 1).as_explicit()
def test_block_index_symbolic():
# Note that these matrices may be zero-sized and indices may be negative, which causes
# all naive simplifications given in the comments to be invalid
A1 = MatrixSymbol('A1', n, k)
A2 = MatrixSymbol('A2', n, l)
A3 = MatrixSymbol('A3', m, k)
A4 = MatrixSymbol('A4', m, l)
A = BlockMatrix([[A1, A2], [A3, A4]])
assert A[0, 0] == MatrixElement(A, 0, 0) # Cannot be A1[0, 0]
assert A[n - 1, k - 1] == A1[n - 1, k - 1]
assert A[n, k] == A4[0, 0]
assert A[n + m - 1, 0] == MatrixElement(A, n + m - 1, 0) # Cannot be A3[m - 1, 0]
assert A[0, k + l - 1] == MatrixElement(A, 0, k + l - 1) # Cannot be A2[0, l - 1]
assert A[n + m - 1, k + l - 1] == MatrixElement(A, n + m - 1, k + l - 1) # Cannot be A4[m - 1, l - 1]
assert A[i, j] == MatrixElement(A, i, j)
assert A[n + i, k + j] == MatrixElement(A, n + i, k + j) # Cannot be A4[i, j]
assert A[n - i - 1, k - j - 1] == MatrixElement(A, n - i - 1, k - j - 1) # Cannot be A1[n - i - 1, k - j - 1]
