public override ECPoint Subtract(ECPoint b)
{
if (b.IsInfinity)
{
return(this);
}
return(Add(b.Negate()));
}
public override ECPoint Subtract(
ECPoint b)
{
if (b.IsInfinity)
return this;
// Add -b
return Add(b.Negate());
}
// D.3.2 pg 102 (see Note:)
public override ECPoint Subtract(ECPoint b)
{
return b.IsInfinity ? this : Add(b.Negate());
}
/**
* Tests <code>ECPoint.add()</code> and <code>ECPoint.subtract()</code>
* for the given point and the given point at infinity.
*
* @param p
* The point on which the tests are performed.
* @param infinity
* The point at infinity on the same curve as <code>p</code>.
*/
private void ImplTestAddSubtract(ECPoint p, ECPoint infinity)
{
AssertPointsEqual("Twice and Add inconsistent", p.Twice(), p.Add(p));
AssertPointsEqual("Twice p - p is not p", p, p.Twice().Subtract(p));
AssertPointsEqual("TwicePlus(p, -p) is not p", p, p.TwicePlus(p.Negate()));
AssertPointsEqual("p - p is not infinity", infinity, p.Subtract(p));
AssertPointsEqual("p plus infinity is not p", p, p.Add(infinity));
AssertPointsEqual("infinity plus p is not p", p, infinity.Add(p));
AssertPointsEqual("infinity plus infinity is not infinity ", infinity, infinity.Add(infinity));
AssertPointsEqual("Twice infinity is not infinity ", infinity, infinity.Twice());
}
// D.3.2 pg 102 (see Note:)
public override ECPoint Subtract(ECPoint b)
{
return(b.IsInfinity ? this : Add(b.Negate()));
}