@Test
public void testMinus() {

    assertCoefficientsEquals(new double[]{A, B, C}, valueOf(A, B, C).minus(0));
    assertCoefficientsEquals(new double[]{A - 2, B, C}, valueOf(A, B, C).minus(2));
    assertCoefficientsEquals(new double[]{0, 0, -C}, valueOf(A, B).minus(valueOf(A, B, C)));
}