/* (non-Javadoc)
* @see Org.BouncyCastle.Math.EC.ECPoint#twice()
*/
public override ECPoint Twice()
{
// Twice identity element (point at infinity) is identity
if (this.IsInfinity)
{
return(this);
}
// if x1 == 0, then (x1, y1) == (x1, x1 + y1)
// and hence this = -this and thus 2(x1, y1) == infinity
if (this.x.ToBigInteger().Sign == 0)
{
return(this.curve.Infinity);
}
F2mFieldElement lambda = (F2mFieldElement)this.x.Add(this.y.Divide(this.x));
F2mFieldElement x2 = (F2mFieldElement)lambda.Square().Add(lambda).Add(this.curve.A);
ECFieldElement ONE = this.curve.FromBigInteger(BigInteger.One);
F2mFieldElement y2 = (F2mFieldElement)this.x.Square().Add(
x2.Multiply(lambda.Add(ONE)));
return(new F2mPoint(this.curve, x2, y2, withCompression));
}