def test_submatrix_of_4x4_is_3x3(self):
a = Matrix([[-6, 1, 1, 6], [-8, 5, 8, 6], [-1, 0, 8, 2],
[-7, 1, -1, 1]])
assert a.submatrix(2, 1) == Matrix([[-6, 1, 6], [-8, 8, 6],
[-7, -1, 1]])
def test_minor_of_3x3(self):
a = Matrix([[3, 5, 0], [2, -1, -7], [6, -1, 5]])
b = a.submatrix(1, 0)
assert b.determinant() == 25
assert a.minor(1, 0) == 25
def test_submatrix_of_3x3_is_2x2(self):
a = Matrix([[1, 5, 0], [-3, 2, 7], [0, 6, -3]])
assert a.submatrix(0, 2) == Matrix([[-3, 2], [0, 6]])