def smith_normal_form(m, domain=None):
'''
Return the Smith Normal Form of a matrix `m` over the ring `domain`.
This will only work if the ring is a principal ideal domain.
Examples
========
>>> from sympy.polys.solvers import RawMatrix as Matrix
>>> from sympy.polys.domains import ZZ
>>> from sympy.matrices.normalforms import smith_normal_form
>>> m = Matrix([[12, 6, 4], [3, 9, 6], [2, 16, 14]])
>>> setattr(m, "ring", ZZ)
>>> print(smith_normal_form(m))
Matrix([[1, 0, 0], [0, 10, 0], [0, 0, -30]])
'''
invs = invariant_factors(m, domain=domain)
smf = diag(*invs)
n = len(invs)
if m.rows > n:
smf = smf.row_insert(m.rows, zeros(m.rows - n, m.cols))
elif m.cols > n:
smf = smf.col_insert(m.cols, zeros(m.rows, m.cols - n))
return smf
def smith_normal_form(m, domain = None):
'''
Return the Smith Normal Form of a matrix `m` over the ring `domain`.
This will only work if the ring is a principal ideal domain.
Examples
========
>>> from sympy.polys.solvers import RawMatrix as Matrix
>>> from sympy.polys.domains import ZZ
>>> from sympy.matrices.normalforms import smith_normal_form
>>> m = Matrix([[12, 6, 4], [3, 9, 6], [2, 16, 14]])
>>> setattr(m, "ring", ZZ)
>>> print(smith_normal_form(m))
Matrix([[1, 0, 0], [0, 10, 0], [0, 0, -30]])
'''
invs = invariant_factors(m, domain=domain)
smf = diag(*invs)
n = len(invs)
if m.rows > n:
smf = smf.row_insert(m.rows, zeros(m.rows-n, m.cols))
elif m.cols > n:
smf = smf.col_insert(m.cols, zeros(m.rows, m.cols-n))
return smf
def get_submatrix(self, matrix):
r"""
Returns
=======
macaulay_submatrix: Matrix
The Macaulay denominator matrix. Columns that are non reduced are kept.
The row which contains one of the a_{i}s is dropped. a_{i}s
are the coefficients of x_i ^ {d_i}.
"""
reduced, non_reduced = self.get_reduced_nonreduced()
# if reduced == [], then det(matrix) should be 1
if reduced == []:
return diag([1])
# reduced != []
reduction_set = [v ** self.degrees[i] for i, v
in enumerate(self.variables)]
ais = list([self.polynomials[i].coeff(reduction_set[i])
for i in range(self.n)])
reduced_matrix = matrix[:, reduced]
keep = []
for row in range(reduced_matrix.rows):
check = [ai in reduced_matrix[row, :] for ai in ais]
if True not in check:
keep.append(row)
return matrix[keep, non_reduced]
def as_explicit(self):
from sympy.matrices.dense import diag
return diag(*list(self._vector.as_explicit()))
def test_replace_arrays_partial_derivative():
x, y, z, t = symbols("x y z t")
# d(A^i)/d(A_j) = d(g^ik A_k)/d(A_j) = g^ik delta_jk
expr = PartialDerivative(A(i), A(-j))
assert expr.get_free_indices() == [i, j]
assert expr.get_indices() == [i, j]
assert expr.replace_with_arrays({A(i): [x, y], L: diag(1, 1)}, [i, j]) == Array([[1, 0], [0, 1]])
assert expr.replace_with_arrays({A(i): [x, y], L: diag(1, -1)}, [i, j]) == Array([[1, 0], [0, -1]])
assert expr.replace_with_arrays({A(-i): [x, y], L: diag(1, 1)}, [i, j]) == Array([[1, 0], [0, 1]])
assert expr.replace_with_arrays({A(-i): [x, y], L: diag(1, -1)}, [i, j]) == Array([[1, 0], [0, -1]])
expr = PartialDerivative(A(i), A(j))
assert expr.get_free_indices() == [i, -j]
assert expr.get_indices() == [i, -j]
assert expr.replace_with_arrays({A(i): [x, y]}, [i, -j]) == Array([[1, 0], [0, 1]])
assert expr.replace_with_arrays({A(i): [x, y], L: diag(1, 1)}, [i, -j]) == Array([[1, 0], [0, 1]])
assert expr.replace_with_arrays({A(i): [x, y], L: diag(1, -1)}, [i, -j]) == Array([[1, 0], [0, 1]])
assert expr.replace_with_arrays({A(-i): [x, y], L: diag(1, 1)}, [i, -j]) == Array([[1, 0], [0, 1]])
assert expr.replace_with_arrays({A(-i): [x, y], L: diag(1, -1)}, [i, -j]) == Array([[1, 0], [0, 1]])
expr = PartialDerivative(A(-i), A(-j))
assert expr.get_free_indices() == [-i, j]
assert expr.get_indices() == [-i, j]
assert expr.replace_with_arrays({A(-i): [x, y]}, [-i, j]) == Array([[1, 0], [0, 1]])
assert expr.replace_with_arrays({A(-i): [x, y], L: diag(1, 1)}, [-i, j]) == Array([[1, 0], [0, 1]])
assert expr.replace_with_arrays({A(-i): [x, y], L: diag(1, -1)}, [-i, j]) == Array([[1, 0], [0, 1]])
assert expr.replace_with_arrays({A(i): [x, y], L: diag(1, 1)}, [-i, j]) == Array([[1, 0], [0, 1]])
assert expr.replace_with_arrays({A(i): [x, y], L: diag(1, -1)}, [-i, j]) == Array([[1, 0], [0, 1]])
expr = PartialDerivative(A(i), A(i))
assert expr.get_free_indices() == []
assert expr.get_indices() == [L_0, -L_0]
assert expr.replace_with_arrays({A(i): [x, y], L: diag(1, 1)}, []) == 2
assert expr.replace_with_arrays({A(i): [x, y], L: diag(1, -1)}, []) == 2
expr = PartialDerivative(A(-i), A(-i))
assert expr.get_free_indices() == []
assert expr.get_indices() == [-L_0, L_0]
assert expr.replace_with_arrays({A(i): [x, y], L: diag(1, 1)}, []) == 2
assert expr.replace_with_arrays({A(i): [x, y], L: diag(1, -1)}, []) == 2
expr = PartialDerivative(H(i, j) + H(j, i), A(i))
assert expr.get_indices() == [L_0, j, -L_0]
assert expr.get_free_indices() == [j]
expr = PartialDerivative(H(i, j) + H(j, i), A(k))*B(-i)
assert expr.get_indices() == [L_0, j, -k, -L_0]
assert expr.get_free_indices() == [j, -k]
expr = PartialDerivative(A(i)*(H(-i, j) + H(j, -i)), A(j))
assert expr.get_indices() == [L_0, -L_0, L_1, -L_1]
assert expr.get_free_indices() == []
expr = A(j)*A(-j) + expr
assert expr.get_indices() == [L_0, -L_0, L_1, -L_1]
assert expr.get_free_indices() == []
expr = A(i)*(B(j)*PartialDerivative(C(-j), D(i)) + C(j)*PartialDerivative(D(-j), B(i)))
assert expr.get_indices() == [L_0, L_1, -L_1, -L_0]
assert expr.get_free_indices() == []
expr = A(i)*PartialDerivative(C(-j), D(i))
assert expr.get_indices() == [L_0, -j, -L_0]
assert expr.get_free_indices() == [-j]
def test_H2():
TP = sympy.diffgeom.TensorProduct
R2 = sympy.diffgeom.rn.R2
y = R2.y
dy = R2.dy
dx = R2.dx
g = (TP(dx, dx) + TP(dy, dy)) * y**(-2)
automat = twoform_to_matrix(g)
mat = diag(y**(-2), y**(-2))
assert mat == automat
gamma1 = metric_to_Christoffel_1st(g)
assert gamma1[0, 0, 0] == 0
assert gamma1[0, 0, 1] == -y**(-3)
assert gamma1[0, 1, 0] == -y**(-3)
assert gamma1[0, 1, 1] == 0
assert gamma1[1, 1, 1] == -y**(-3)
assert gamma1[1, 1, 0] == 0
assert gamma1[1, 0, 1] == 0
assert gamma1[1, 0, 0] == y**(-3)
gamma2 = metric_to_Christoffel_2nd(g)
assert gamma2[0, 0, 0] == 0
assert gamma2[0, 0, 1] == -y**(-1)
assert gamma2[0, 1, 0] == -y**(-1)
assert gamma2[0, 1, 1] == 0
assert gamma2[1, 1, 1] == -y**(-1)
assert gamma2[1, 1, 0] == 0
assert gamma2[1, 0, 1] == 0
assert gamma2[1, 0, 0] == y**(-1)
Rm = metric_to_Riemann_components(g)
assert Rm[0, 0, 0, 0] == 0
assert Rm[0, 0, 0, 1] == 0
assert Rm[0, 0, 1, 0] == 0
assert Rm[0, 0, 1, 1] == 0
assert Rm[0, 1, 0, 0] == 0
assert Rm[0, 1, 0, 1] == -y**(-2)
assert Rm[0, 1, 1, 0] == y**(-2)
assert Rm[0, 1, 1, 1] == 0
assert Rm[1, 0, 0, 0] == 0
assert Rm[1, 0, 0, 1] == y**(-2)
assert Rm[1, 0, 1, 0] == -y**(-2)
assert Rm[1, 0, 1, 1] == 0
assert Rm[1, 1, 0, 0] == 0
assert Rm[1, 1, 0, 1] == 0
assert Rm[1, 1, 1, 0] == 0
assert Rm[1, 1, 1, 1] == 0
Ric = metric_to_Ricci_components(g)
assert Ric[0, 0] == -y**(-2)
assert Ric[0, 1] == 0
assert Ric[1, 0] == 0
assert Ric[0, 0] == -y**(-2)
assert Ric == ImmutableDenseNDimArray([-y**(-2), 0, 0, -y**(-2)], (2, 2))
## scalar curvature is -2
#TODO - it would be nice to have index contraction built-in
R = (Ric[0, 0] + Ric[1, 1]) * y**2
assert R == -2
## Gauss curvature is -1
assert R / 2 == -1