Example #1
0
static
void compute_a_vals(Vec<ZZ>& a, long p, long e)
// computes a[m] = a(m)/m! for m = p..(e-1)(p-1)+1,
// as defined by Chen and Han.
// a.length() is set to (e-1)(p-1)+2

{
   ZZ p_to_e = power_ZZ(p, e);
   ZZ p_to_2e = power_ZZ(p, 2*e);

   long len = (e-1)*(p-1)+2;

   ZZ_pPush push(p_to_2e);

   ZZ_pX x_plus_1_to_p = power(ZZ_pX(INIT_MONO, 1) + 1, p);
   ZZ_pX denom = InvTrunc(x_plus_1_to_p - ZZ_pX(INIT_MONO, p), len);
   ZZ_pX poly = MulTrunc(x_plus_1_to_p, denom, len);
   poly *= p;

   a.SetLength(len);

   ZZ m_fac(1);
   for (long m = 2; m < p; m++) {
      m_fac = MulMod(m_fac, m, p_to_2e);
   }

   for (long m = p; m < len; m++) {
      m_fac = MulMod(m_fac, m, p_to_2e);
      ZZ c = rep(coeff(poly, m));
      ZZ d = GCD(m_fac, p_to_2e);
      if (d == 0 || d > p_to_e || c % d != 0) Error("cannot divide");
      ZZ m_fac_deflated = (m_fac / d) % p_to_e;
      ZZ c_deflated = (c / d) % p_to_e;
      a[m] = MulMod(c_deflated, InvMod(m_fac_deflated, p_to_e), p_to_e);
   }

}
Example #2
0
static CYTHON_INLINE struct ZZ_pX ZZ_pE_to_ZZ_pX(struct ZZ_pE x)
{
    return ZZ_pX(rep(x));
}