/* this=1/this */
public void inverse()
{
norm();
FP2 t1 = new FP2(a);
FP2 t2 = new FP2(b);
t1.sqr();
t2.sqr();
t2.mul_ip();
t1.sub(t2);
t1.inverse();
a.mul(t1);
t1.neg();
b.mul(t1);
}
/* normalises m-array of ECP2 points. Requires work vector of m FP2s */
public static void multiaffine(int m, ECP2[] P)
{
int i;
FP2 t1 = new FP2(0);
FP2 t2 = new FP2(0);
FP2[] work = new FP2[m];
work[0] = new FP2(1);
work[1] = new FP2(P[0].z);
for (i = 2; i < m; i++)
{
work[i] = new FP2(work[i - 1]);
work[i].mul(P[i - 1].z);
}
t1.copy(work[m - 1]);
t1.mul(P[m - 1].z);
t1.inverse();
t2.copy(P[m - 1].z);
work[m - 1].mul(t1);
for (i = m - 2;; i--)
{
if (i == 0)
{
work[0].copy(t1);
work[0].mul(t2);
break;
}
work[i].mul(t2);
work[i].mul(t1);
t2.mul(P[i].z);
}
/* now work[] contains inverses of all Z coordinates */
for (i = 0; i < m; i++)
{
P[i].z.one();
t1.copy(work[i]);
t1.sqr();
P[i].x.mul(t1);
t1.mul(work[i]);
P[i].y.mul(t1);
}
}
/* set to Affine - (x,y,z) to (x,y) */
public void affine()
{
if (is_infinity())
{
return;
}
FP2 one = new FP2(1);
if (z.Equals(one))
{
return;
}
z.inverse();
FP2 z2 = new FP2(z);
z2.sqr();
x.mul(z2);
x.reduce();
y.mul(z2);
y.mul(z);
y.reduce();
z.copy(one);
}