ai-content-maker/.venv/Lib/site-packages/sympy/polys/matrices/tests/test_ddm.py

558 lines
16 KiB
Python

from sympy.testing.pytest import raises
from sympy.external.gmpy import HAS_GMPY
from sympy.polys import ZZ, QQ
from sympy.polys.matrices.ddm import DDM
from sympy.polys.matrices.exceptions import (
DMShapeError, DMNonInvertibleMatrixError, DMDomainError,
DMBadInputError)
def test_DDM_init():
items = [[ZZ(0), ZZ(1), ZZ(2)], [ZZ(3), ZZ(4), ZZ(5)]]
shape = (2, 3)
ddm = DDM(items, shape, ZZ)
assert ddm.shape == shape
assert ddm.rows == 2
assert ddm.cols == 3
assert ddm.domain == ZZ
raises(DMBadInputError, lambda: DDM([[ZZ(2), ZZ(3)]], (2, 2), ZZ))
raises(DMBadInputError, lambda: DDM([[ZZ(1)], [ZZ(2), ZZ(3)]], (2, 2), ZZ))
def test_DDM_getsetitem():
ddm = DDM([[ZZ(2), ZZ(3)], [ZZ(4), ZZ(5)]], (2, 2), ZZ)
assert ddm[0][0] == ZZ(2)
assert ddm[0][1] == ZZ(3)
assert ddm[1][0] == ZZ(4)
assert ddm[1][1] == ZZ(5)
raises(IndexError, lambda: ddm[2][0])
raises(IndexError, lambda: ddm[0][2])
ddm[0][0] = ZZ(-1)
assert ddm[0][0] == ZZ(-1)
def test_DDM_str():
ddm = DDM([[ZZ(0), ZZ(1)], [ZZ(2), ZZ(3)]], (2, 2), ZZ)
if HAS_GMPY: # pragma: no cover
assert str(ddm) == '[[0, 1], [2, 3]]'
assert repr(ddm) == 'DDM([[mpz(0), mpz(1)], [mpz(2), mpz(3)]], (2, 2), ZZ)'
else: # pragma: no cover
assert repr(ddm) == 'DDM([[0, 1], [2, 3]], (2, 2), ZZ)'
assert str(ddm) == '[[0, 1], [2, 3]]'
def test_DDM_eq():
items = [[ZZ(0), ZZ(1)], [ZZ(2), ZZ(3)]]
ddm1 = DDM(items, (2, 2), ZZ)
ddm2 = DDM(items, (2, 2), ZZ)
assert (ddm1 == ddm1) is True
assert (ddm1 == items) is False
assert (items == ddm1) is False
assert (ddm1 == ddm2) is True
assert (ddm2 == ddm1) is True
assert (ddm1 != ddm1) is False
assert (ddm1 != items) is True
assert (items != ddm1) is True
assert (ddm1 != ddm2) is False
assert (ddm2 != ddm1) is False
ddm3 = DDM([[ZZ(0), ZZ(1)], [ZZ(3), ZZ(3)]], (2, 2), ZZ)
ddm3 = DDM(items, (2, 2), QQ)
assert (ddm1 == ddm3) is False
assert (ddm3 == ddm1) is False
assert (ddm1 != ddm3) is True
assert (ddm3 != ddm1) is True
def test_DDM_convert_to():
ddm = DDM([[ZZ(1), ZZ(2)]], (1, 2), ZZ)
assert ddm.convert_to(ZZ) == ddm
ddmq = ddm.convert_to(QQ)
assert ddmq.domain == QQ
def test_DDM_zeros():
ddmz = DDM.zeros((3, 4), QQ)
assert list(ddmz) == [[QQ(0)] * 4] * 3
assert ddmz.shape == (3, 4)
assert ddmz.domain == QQ
def test_DDM_ones():
ddmone = DDM.ones((2, 3), QQ)
assert list(ddmone) == [[QQ(1)] * 3] * 2
assert ddmone.shape == (2, 3)
assert ddmone.domain == QQ
def test_DDM_eye():
ddmz = DDM.eye(3, QQ)
f = lambda i, j: QQ(1) if i == j else QQ(0)
assert list(ddmz) == [[f(i, j) for i in range(3)] for j in range(3)]
assert ddmz.shape == (3, 3)
assert ddmz.domain == QQ
def test_DDM_copy():
ddm1 = DDM([[QQ(1)], [QQ(2)]], (2, 1), QQ)
ddm2 = ddm1.copy()
assert (ddm1 == ddm2) is True
ddm1[0][0] = QQ(-1)
assert (ddm1 == ddm2) is False
ddm2[0][0] = QQ(-1)
assert (ddm1 == ddm2) is True
def test_DDM_transpose():
ddm = DDM([[QQ(1)], [QQ(2)]], (2, 1), QQ)
ddmT = DDM([[QQ(1), QQ(2)]], (1, 2), QQ)
assert ddm.transpose() == ddmT
ddm02 = DDM([], (0, 2), QQ)
ddm02T = DDM([[], []], (2, 0), QQ)
assert ddm02.transpose() == ddm02T
assert ddm02T.transpose() == ddm02
ddm0 = DDM([], (0, 0), QQ)
assert ddm0.transpose() == ddm0
def test_DDM_add():
A = DDM([[ZZ(1)], [ZZ(2)]], (2, 1), ZZ)
B = DDM([[ZZ(3)], [ZZ(4)]], (2, 1), ZZ)
C = DDM([[ZZ(4)], [ZZ(6)]], (2, 1), ZZ)
AQ = DDM([[QQ(1)], [QQ(2)]], (2, 1), QQ)
assert A + B == A.add(B) == C
raises(DMShapeError, lambda: A + DDM([[ZZ(5)]], (1, 1), ZZ))
raises(TypeError, lambda: A + ZZ(1))
raises(TypeError, lambda: ZZ(1) + A)
raises(DMDomainError, lambda: A + AQ)
raises(DMDomainError, lambda: AQ + A)
def test_DDM_sub():
A = DDM([[ZZ(1)], [ZZ(2)]], (2, 1), ZZ)
B = DDM([[ZZ(3)], [ZZ(4)]], (2, 1), ZZ)
C = DDM([[ZZ(-2)], [ZZ(-2)]], (2, 1), ZZ)
AQ = DDM([[QQ(1)], [QQ(2)]], (2, 1), QQ)
D = DDM([[ZZ(5)]], (1, 1), ZZ)
assert A - B == A.sub(B) == C
raises(TypeError, lambda: A - ZZ(1))
raises(TypeError, lambda: ZZ(1) - A)
raises(DMShapeError, lambda: A - D)
raises(DMShapeError, lambda: D - A)
raises(DMShapeError, lambda: A.sub(D))
raises(DMShapeError, lambda: D.sub(A))
raises(DMDomainError, lambda: A - AQ)
raises(DMDomainError, lambda: AQ - A)
raises(DMDomainError, lambda: A.sub(AQ))
raises(DMDomainError, lambda: AQ.sub(A))
def test_DDM_neg():
A = DDM([[ZZ(1)], [ZZ(2)]], (2, 1), ZZ)
An = DDM([[ZZ(-1)], [ZZ(-2)]], (2, 1), ZZ)
assert -A == A.neg() == An
assert -An == An.neg() == A
def test_DDM_mul():
A = DDM([[ZZ(1)]], (1, 1), ZZ)
A2 = DDM([[ZZ(2)]], (1, 1), ZZ)
assert A * ZZ(2) == A2
assert ZZ(2) * A == A2
raises(TypeError, lambda: [[1]] * A)
raises(TypeError, lambda: A * [[1]])
def test_DDM_matmul():
A = DDM([[ZZ(1)], [ZZ(2)]], (2, 1), ZZ)
B = DDM([[ZZ(3), ZZ(4)]], (1, 2), ZZ)
AB = DDM([[ZZ(3), ZZ(4)], [ZZ(6), ZZ(8)]], (2, 2), ZZ)
BA = DDM([[ZZ(11)]], (1, 1), ZZ)
assert A @ B == A.matmul(B) == AB
assert B @ A == B.matmul(A) == BA
raises(TypeError, lambda: A @ 1)
raises(TypeError, lambda: A @ [[3, 4]])
Bq = DDM([[QQ(3), QQ(4)]], (1, 2), QQ)
raises(DMDomainError, lambda: A @ Bq)
raises(DMDomainError, lambda: Bq @ A)
C = DDM([[ZZ(1)]], (1, 1), ZZ)
assert A @ C == A.matmul(C) == A
raises(DMShapeError, lambda: C @ A)
raises(DMShapeError, lambda: C.matmul(A))
Z04 = DDM([], (0, 4), ZZ)
Z40 = DDM([[]]*4, (4, 0), ZZ)
Z50 = DDM([[]]*5, (5, 0), ZZ)
Z05 = DDM([], (0, 5), ZZ)
Z45 = DDM([[0] * 5] * 4, (4, 5), ZZ)
Z54 = DDM([[0] * 4] * 5, (5, 4), ZZ)
Z00 = DDM([], (0, 0), ZZ)
assert Z04 @ Z45 == Z04.matmul(Z45) == Z05
assert Z45 @ Z50 == Z45.matmul(Z50) == Z40
assert Z00 @ Z04 == Z00.matmul(Z04) == Z04
assert Z50 @ Z00 == Z50.matmul(Z00) == Z50
assert Z00 @ Z00 == Z00.matmul(Z00) == Z00
assert Z50 @ Z04 == Z50.matmul(Z04) == Z54
raises(DMShapeError, lambda: Z05 @ Z40)
raises(DMShapeError, lambda: Z05.matmul(Z40))
def test_DDM_hstack():
A = DDM([[ZZ(1), ZZ(2), ZZ(3)]], (1, 3), ZZ)
B = DDM([[ZZ(4), ZZ(5)]], (1, 2), ZZ)
C = DDM([[ZZ(6)]], (1, 1), ZZ)
Ah = A.hstack(B)
assert Ah.shape == (1, 5)
assert Ah.domain == ZZ
assert Ah == DDM([[ZZ(1), ZZ(2), ZZ(3), ZZ(4), ZZ(5)]], (1, 5), ZZ)
Ah = A.hstack(B, C)
assert Ah.shape == (1, 6)
assert Ah.domain == ZZ
assert Ah == DDM([[ZZ(1), ZZ(2), ZZ(3), ZZ(4), ZZ(5), ZZ(6)]], (1, 6), ZZ)
def test_DDM_vstack():
A = DDM([[ZZ(1)], [ZZ(2)], [ZZ(3)]], (3, 1), ZZ)
B = DDM([[ZZ(4)], [ZZ(5)]], (2, 1), ZZ)
C = DDM([[ZZ(6)]], (1, 1), ZZ)
Ah = A.vstack(B)
assert Ah.shape == (5, 1)
assert Ah.domain == ZZ
assert Ah == DDM([[ZZ(1)], [ZZ(2)], [ZZ(3)], [ZZ(4)], [ZZ(5)]], (5, 1), ZZ)
Ah = A.vstack(B, C)
assert Ah.shape == (6, 1)
assert Ah.domain == ZZ
assert Ah == DDM([[ZZ(1)], [ZZ(2)], [ZZ(3)], [ZZ(4)], [ZZ(5)], [ZZ(6)]], (6, 1), ZZ)
def test_DDM_applyfunc():
A = DDM([[ZZ(1), ZZ(2), ZZ(3)]], (1, 3), ZZ)
B = DDM([[ZZ(2), ZZ(4), ZZ(6)]], (1, 3), ZZ)
assert A.applyfunc(lambda x: 2*x, ZZ) == B
def test_DDM_rref():
A = DDM([], (0, 4), QQ)
assert A.rref() == (A, [])
A = DDM([[QQ(0), QQ(1)], [QQ(1), QQ(1)]], (2, 2), QQ)
Ar = DDM([[QQ(1), QQ(0)], [QQ(0), QQ(1)]], (2, 2), QQ)
pivots = [0, 1]
assert A.rref() == (Ar, pivots)
A = DDM([[QQ(1), QQ(2), QQ(1)], [QQ(3), QQ(4), QQ(1)]], (2, 3), QQ)
Ar = DDM([[QQ(1), QQ(0), QQ(-1)], [QQ(0), QQ(1), QQ(1)]], (2, 3), QQ)
pivots = [0, 1]
assert A.rref() == (Ar, pivots)
A = DDM([[QQ(3), QQ(4), QQ(1)], [QQ(1), QQ(2), QQ(1)]], (2, 3), QQ)
Ar = DDM([[QQ(1), QQ(0), QQ(-1)], [QQ(0), QQ(1), QQ(1)]], (2, 3), QQ)
pivots = [0, 1]
assert A.rref() == (Ar, pivots)
A = DDM([[QQ(1), QQ(0)], [QQ(1), QQ(3)], [QQ(0), QQ(1)]], (3, 2), QQ)
Ar = DDM([[QQ(1), QQ(0)], [QQ(0), QQ(1)], [QQ(0), QQ(0)]], (3, 2), QQ)
pivots = [0, 1]
assert A.rref() == (Ar, pivots)
A = DDM([[QQ(1), QQ(0), QQ(1)], [QQ(3), QQ(0), QQ(1)]], (2, 3), QQ)
Ar = DDM([[QQ(1), QQ(0), QQ(0)], [QQ(0), QQ(0), QQ(1)]], (2, 3), QQ)
pivots = [0, 2]
assert A.rref() == (Ar, pivots)
def test_DDM_nullspace():
A = DDM([[QQ(1), QQ(1)], [QQ(1), QQ(1)]], (2, 2), QQ)
Anull = DDM([[QQ(-1), QQ(1)]], (1, 2), QQ)
nonpivots = [1]
assert A.nullspace() == (Anull, nonpivots)
def test_DDM_particular():
A = DDM([[QQ(1), QQ(0)]], (1, 2), QQ)
assert A.particular() == DDM.zeros((1, 1), QQ)
def test_DDM_det():
# 0x0 case
A = DDM([], (0, 0), ZZ)
assert A.det() == ZZ(1)
# 1x1 case
A = DDM([[ZZ(2)]], (1, 1), ZZ)
assert A.det() == ZZ(2)
# 2x2 case
A = DDM([[ZZ(1), ZZ(2)], [ZZ(3), ZZ(4)]], (2, 2), ZZ)
assert A.det() == ZZ(-2)
# 3x3 with swap
A = DDM([[ZZ(1), ZZ(2), ZZ(3)], [ZZ(1), ZZ(2), ZZ(4)], [ZZ(1), ZZ(2), ZZ(5)]], (3, 3), ZZ)
assert A.det() == ZZ(0)
# 2x2 QQ case
A = DDM([[QQ(1, 2), QQ(1, 2)], [QQ(1, 3), QQ(1, 4)]], (2, 2), QQ)
assert A.det() == QQ(-1, 24)
# Nonsquare error
A = DDM([[ZZ(1)], [ZZ(2)]], (2, 1), ZZ)
raises(DMShapeError, lambda: A.det())
# Nonsquare error with empty matrix
A = DDM([], (0, 1), ZZ)
raises(DMShapeError, lambda: A.det())
def test_DDM_inv():
A = DDM([[QQ(1, 1), QQ(2, 1)], [QQ(3, 1), QQ(4, 1)]], (2, 2), QQ)
Ainv = DDM([[QQ(-2, 1), QQ(1, 1)], [QQ(3, 2), QQ(-1, 2)]], (2, 2), QQ)
assert A.inv() == Ainv
A = DDM([[QQ(1), QQ(2)]], (1, 2), QQ)
raises(DMShapeError, lambda: A.inv())
A = DDM([[ZZ(2)]], (1, 1), ZZ)
raises(ValueError, lambda: A.inv())
A = DDM([], (0, 0), QQ)
assert A.inv() == A
A = DDM([[QQ(1), QQ(2)], [QQ(2), QQ(4)]], (2, 2), QQ)
raises(DMNonInvertibleMatrixError, lambda: A.inv())
def test_DDM_lu():
A = DDM([[QQ(1), QQ(2)], [QQ(3), QQ(4)]], (2, 2), QQ)
L, U, swaps = A.lu()
assert L == DDM([[QQ(1), QQ(0)], [QQ(3), QQ(1)]], (2, 2), QQ)
assert U == DDM([[QQ(1), QQ(2)], [QQ(0), QQ(-2)]], (2, 2), QQ)
assert swaps == []
A = [[1, 0, 0, 0], [0, 0, 0, 0], [0, 0, 1, 1], [0, 0, 1, 2]]
Lexp = [[1, 0, 0, 0], [0, 1, 0, 0], [0, 0, 1, 0], [0, 0, 1, 1]]
Uexp = [[1, 0, 0, 0], [0, 0, 0, 0], [0, 0, 1, 1], [0, 0, 0, 1]]
to_dom = lambda rows, dom: [[dom(e) for e in row] for row in rows]
A = DDM(to_dom(A, QQ), (4, 4), QQ)
Lexp = DDM(to_dom(Lexp, QQ), (4, 4), QQ)
Uexp = DDM(to_dom(Uexp, QQ), (4, 4), QQ)
L, U, swaps = A.lu()
assert L == Lexp
assert U == Uexp
assert swaps == []
def test_DDM_lu_solve():
# Basic example
A = DDM([[QQ(1), QQ(2)], [QQ(3), QQ(4)]], (2, 2), QQ)
b = DDM([[QQ(1)], [QQ(2)]], (2, 1), QQ)
x = DDM([[QQ(0)], [QQ(1, 2)]], (2, 1), QQ)
assert A.lu_solve(b) == x
# Example with swaps
A = DDM([[QQ(0), QQ(2)], [QQ(3), QQ(4)]], (2, 2), QQ)
assert A.lu_solve(b) == x
# Overdetermined, consistent
A = DDM([[QQ(1), QQ(2)], [QQ(3), QQ(4)], [QQ(5), QQ(6)]], (3, 2), QQ)
b = DDM([[QQ(1)], [QQ(2)], [QQ(3)]], (3, 1), QQ)
assert A.lu_solve(b) == x
# Overdetermined, inconsistent
b = DDM([[QQ(1)], [QQ(2)], [QQ(4)]], (3, 1), QQ)
raises(DMNonInvertibleMatrixError, lambda: A.lu_solve(b))
# Square, noninvertible
A = DDM([[QQ(1), QQ(2)], [QQ(1), QQ(2)]], (2, 2), QQ)
b = DDM([[QQ(1)], [QQ(2)]], (2, 1), QQ)
raises(DMNonInvertibleMatrixError, lambda: A.lu_solve(b))
# Underdetermined
A = DDM([[QQ(1), QQ(2)]], (1, 2), QQ)
b = DDM([[QQ(3)]], (1, 1), QQ)
raises(NotImplementedError, lambda: A.lu_solve(b))
# Domain mismatch
bz = DDM([[ZZ(1)], [ZZ(2)]], (2, 1), ZZ)
raises(DMDomainError, lambda: A.lu_solve(bz))
# Shape mismatch
b3 = DDM([[QQ(1)], [QQ(2)], [QQ(3)]], (3, 1), QQ)
raises(DMShapeError, lambda: A.lu_solve(b3))
def test_DDM_charpoly():
A = DDM([], (0, 0), ZZ)
assert A.charpoly() == [ZZ(1)]
A = DDM([
[ZZ(1), ZZ(2), ZZ(3)],
[ZZ(4), ZZ(5), ZZ(6)],
[ZZ(7), ZZ(8), ZZ(9)]], (3, 3), ZZ)
Avec = [ZZ(1), ZZ(-15), ZZ(-18), ZZ(0)]
assert A.charpoly() == Avec
A = DDM([[ZZ(1), ZZ(2)]], (1, 2), ZZ)
raises(DMShapeError, lambda: A.charpoly())
def test_DDM_getitem():
dm = DDM([
[ZZ(1), ZZ(2), ZZ(3)],
[ZZ(4), ZZ(5), ZZ(6)],
[ZZ(7), ZZ(8), ZZ(9)]], (3, 3), ZZ)
assert dm.getitem(1, 1) == ZZ(5)
assert dm.getitem(1, -2) == ZZ(5)
assert dm.getitem(-1, -3) == ZZ(7)
raises(IndexError, lambda: dm.getitem(3, 3))
def test_DDM_setitem():
dm = DDM.zeros((3, 3), ZZ)
dm.setitem(0, 0, 1)
dm.setitem(1, -2, 1)
dm.setitem(-1, -1, 1)
assert dm == DDM.eye(3, ZZ)
raises(IndexError, lambda: dm.setitem(3, 3, 0))
def test_DDM_extract_slice():
dm = DDM([
[ZZ(1), ZZ(2), ZZ(3)],
[ZZ(4), ZZ(5), ZZ(6)],
[ZZ(7), ZZ(8), ZZ(9)]], (3, 3), ZZ)
assert dm.extract_slice(slice(0, 3), slice(0, 3)) == dm
assert dm.extract_slice(slice(1, 3), slice(-2)) == DDM([[4], [7]], (2, 1), ZZ)
assert dm.extract_slice(slice(1, 3), slice(-2)) == DDM([[4], [7]], (2, 1), ZZ)
assert dm.extract_slice(slice(2, 3), slice(-2)) == DDM([[ZZ(7)]], (1, 1), ZZ)
assert dm.extract_slice(slice(0, 2), slice(-2)) == DDM([[1], [4]], (2, 1), ZZ)
assert dm.extract_slice(slice(-1), slice(-1)) == DDM([[1, 2], [4, 5]], (2, 2), ZZ)
assert dm.extract_slice(slice(2), slice(3, 4)) == DDM([[], []], (2, 0), ZZ)
assert dm.extract_slice(slice(3, 4), slice(2)) == DDM([], (0, 2), ZZ)
assert dm.extract_slice(slice(3, 4), slice(3, 4)) == DDM([], (0, 0), ZZ)
def test_DDM_extract():
dm1 = DDM([
[ZZ(1), ZZ(2), ZZ(3)],
[ZZ(4), ZZ(5), ZZ(6)],
[ZZ(7), ZZ(8), ZZ(9)]], (3, 3), ZZ)
dm2 = DDM([
[ZZ(6), ZZ(4)],
[ZZ(3), ZZ(1)]], (2, 2), ZZ)
assert dm1.extract([1, 0], [2, 0]) == dm2
assert dm1.extract([-2, 0], [-1, 0]) == dm2
assert dm1.extract([], []) == DDM.zeros((0, 0), ZZ)
assert dm1.extract([1], []) == DDM.zeros((1, 0), ZZ)
assert dm1.extract([], [1]) == DDM.zeros((0, 1), ZZ)
raises(IndexError, lambda: dm2.extract([2], [0]))
raises(IndexError, lambda: dm2.extract([0], [2]))
raises(IndexError, lambda: dm2.extract([-3], [0]))
raises(IndexError, lambda: dm2.extract([0], [-3]))
def test_DDM_flat():
dm = DDM([
[ZZ(6), ZZ(4)],
[ZZ(3), ZZ(1)]], (2, 2), ZZ)
assert dm.flat() == [ZZ(6), ZZ(4), ZZ(3), ZZ(1)]
def test_DDM_is_zero_matrix():
A = DDM([[QQ(1), QQ(0)], [QQ(0), QQ(0)]], (2, 2), QQ)
Azero = DDM.zeros((1, 2), QQ)
assert A.is_zero_matrix() is False
assert Azero.is_zero_matrix() is True
def test_DDM_is_upper():
# Wide matrices:
A = DDM([
[QQ(1), QQ(2), QQ(3), QQ(4)],
[QQ(0), QQ(5), QQ(6), QQ(7)],
[QQ(0), QQ(0), QQ(8), QQ(9)]
], (3, 4), QQ)
B = DDM([
[QQ(1), QQ(2), QQ(3), QQ(4)],
[QQ(0), QQ(5), QQ(6), QQ(7)],
[QQ(0), QQ(7), QQ(8), QQ(9)]
], (3, 4), QQ)
assert A.is_upper() is True
assert B.is_upper() is False
# Tall matrices:
A = DDM([
[QQ(1), QQ(2), QQ(3)],
[QQ(0), QQ(5), QQ(6)],
[QQ(0), QQ(0), QQ(8)],
[QQ(0), QQ(0), QQ(0)]
], (4, 3), QQ)
B = DDM([
[QQ(1), QQ(2), QQ(3)],
[QQ(0), QQ(5), QQ(6)],
[QQ(0), QQ(0), QQ(8)],
[QQ(0), QQ(0), QQ(10)]
], (4, 3), QQ)
assert A.is_upper() is True
assert B.is_upper() is False
def test_DDM_is_lower():
# Tall matrices:
A = DDM([
[QQ(1), QQ(2), QQ(3), QQ(4)],
[QQ(0), QQ(5), QQ(6), QQ(7)],
[QQ(0), QQ(0), QQ(8), QQ(9)]
], (3, 4), QQ).transpose()
B = DDM([
[QQ(1), QQ(2), QQ(3), QQ(4)],
[QQ(0), QQ(5), QQ(6), QQ(7)],
[QQ(0), QQ(7), QQ(8), QQ(9)]
], (3, 4), QQ).transpose()
assert A.is_lower() is True
assert B.is_lower() is False
# Wide matrices:
A = DDM([
[QQ(1), QQ(2), QQ(3)],
[QQ(0), QQ(5), QQ(6)],
[QQ(0), QQ(0), QQ(8)],
[QQ(0), QQ(0), QQ(0)]
], (4, 3), QQ).transpose()
B = DDM([
[QQ(1), QQ(2), QQ(3)],
[QQ(0), QQ(5), QQ(6)],
[QQ(0), QQ(0), QQ(8)],
[QQ(0), QQ(0), QQ(10)]
], (4, 3), QQ).transpose()
assert A.is_lower() is True
assert B.is_lower() is False