def test_BlockMatrix_2x2_inverse_numeric(): """Test 2x2 block matrix inversion numerically for all 4 formulas""" M = Matrix([[1, 2], [3, 4]]) # rank deficient matrices that have full rank when two of them combined D1 = Matrix([[1, 2], [2, 4]]) D2 = Matrix([[1, 3], [3, 9]]) D3 = Matrix([[1, 4], [4, 16]]) assert D1.rank() == D2.rank() == D3.rank() == 1 assert (D1 + D2).rank() == (D2 + D3).rank() == (D3 + D1).rank() == 2 # Only A is invertible K = BlockMatrix([[M, D1], [D2, D3]]) assert block_collapse(K.inv()).as_explicit() == K.as_explicit().inv() # Only B is invertible K = BlockMatrix([[D1, M], [D2, D3]]) assert block_collapse(K.inv()).as_explicit() == K.as_explicit().inv() # Only C is invertible K = BlockMatrix([[D1, D2], [M, D3]]) assert block_collapse(K.inv()).as_explicit() == K.as_explicit().inv() # Only D is invertible K = BlockMatrix([[D1, D2], [D3, M]]) assert block_collapse(K.inv()).as_explicit() == K.as_explicit().inv()
def test_issue_21866(): n = 10 I = Identity(n) O = ZeroMatrix(n, n) A = BlockMatrix([[ I, O, O, O ], [ O, I, O, O ], [ O, O, I, O ], [ I, O, O, I ]]) Ainv = block_collapse(A.inv()) AinvT = BlockMatrix([[ I, O, O, O ], [ O, I, O, O ], [ O, O, I, O ], [ -I, O, O, I ]]) assert Ainv == AinvT