public boolean isParallel(Vector2D v) { return 0.0 == CGAlgorithmsDD.signOfDet2x2(x, y, v.x, v.y); }
private void checkSignOfDet2x2(double x1, double y1, double x2, double y2, int sign) { assertEquals(sign, CGAlgorithmsDD.signOfDet2x2(x1, y1, x2, y2)); } }