void testFactorization(Matrix A, Vector x) {
Vector b = A.mult(x, x.copy());
ILU ilut = new ILU(new CompRowMatrix(A));
ilut.setMatrix(A);
ilut.apply(b, x);
Vector r = A.multAdd(-1, x, b.copy());
assertEquals(0, r.norm(Vector.Norm.TwoRobust), 1e-5);
}