def test_inversion(self): m = Matrix(vals=[ [6, 4, 4, 4], [5, 5, 7, 6], [4, -9, 3, -7], [9, 1, 7, -6], ]) self.assertEqual(m._determinant(), -2120) # verify exception if determinant is zero m = Matrix( vals=[[-4, 2, -2, -3], [9, 6, 2, 6], [0, -5, 1, -5], [0, 0, 0, 0]]) self.assertEqual(m._determinant(), 0) with self.assertRaises(ValueError): m.inverse() m = Matrix(vals=[ [-5, 2, 6, -8], [1, -5, 1, 8], [7, 7, -6, -7], [1, -3, 7, 4], ]) self.assertMatrixEqual( m.inverse(), Matrix(vals=[[0.21805, 0.45113, 0.24060, -0.04511], [-0.80827, -1.45677, -0.44361, 0.52068], [-0.07895, -0.22368, -0.05263, 0.19737], [-0.52256, -0.81391, -0.30075, 0.30639]])) m = Matrix( vals=[[8, -5, 9, 2], [7, 5, 6, 1], [-6, 0, 9, 6], [-3, 0, -9, -4]]) self.assertMatrixEqual( m.inverse(), Matrix(vals=[[-0.15385, -0.15385, -0.28205, -0.53846], [-0.07692, 0.12308, 0.02564, 0.03077], [0.35897, 0.35897, 0.43590, 0.92308], [-0.69231, -0.69231, -0.76923, -1.92308]])) m = Matrix(vals=[[9, 3, 0, 9], [-5, -2, -6, -3], [-4, 9, 6, 4], [-7, 6, 6, 2]]) self.assertMatrixEqual( m.inverse(), Matrix(vals=[[-0.04074, -0.07778, 0.14444, -0.22222], [-0.07778, 0.03333, 0.36667, -0.33333], [-0.02901, -0.14630, -0.10926, 0.12963], [0.17778, 0.06667, -0.26667, 0.33333]])) a = Matrix(vals=[[3, -9, 7, 3], [3, -8, 2, -9], [-4, 4, 4, 1], [-6, 5, -1, 1]]) b = Matrix( vals=[[8, 2, 2, 2], [3, -1, 7, 0], [7, 0, 5, 4], [6, -2, 0, 5]]) c = a * b self.assertMatrixEqual(c * b.inverse(), a)
def test_determinant_3x3(self): m = Matrix(vals=[[1, 2, 6], [-5, 8, -4], [2, 6, 4]]) self.assertEqual(m._determinant(), -196)
def test_determinant_4x4(self): m = Matrix(vals=[[-2, -8, 3, 5], [-3, 1, 7, 3], [1, 2, -9, 6], [-6, 7, 7, -9]]) self.assertEqual(m._determinant(), -4071)
def test_determinant_2x2(self): m = Matrix(vals=[[1, 5], [-3, 2]]) self.assertEqual(m._determinant(), 17)