static struct xpr
rred (struct xpr z, int kf, int *ps)
{
struct xpr is, q;
if (x_neg (&z))
{
z = xneg (z);
is = xOne;
}
else
is = xZero;
z = xfmod (z, xPi, &q);
if (kf == 't')
q = is;
else if (kf == 's')
q = xadd (q, is, 0);
if (xprcmp (&z, &xPi2) == 1)
{
z = xadd (xPi, z, 1);
if (kf == 'c' || kf == 't')
q = xadd (q, xOne, 0);
}
*ps = (xodd (q)) ? 1 : 0;
return z;
}
bool Hexagon::less(const Hexagon *h) const
{
if (y() < h->y())
return true;
if (y() > h->y())
return false;
if (xeven() && h->xodd())
return true;
if (xodd() && h->xeven())
return false;
return x() < h->x();
}
