sage: X = random_matrix(F, n)
sage: Y = random_matrix(F, n)
sage: actual = _embed_complex_matrix(X) * _embed_complex_matrix(Y)
sage: X = random_matrix(F, n)
sage: Y = random_matrix(F, n)
sage: actual = _embed_complex_matrix(X) * _embed_complex_matrix(Y)