power_mod()

TowerPolynomial DPoly::power_mod	(	int	level,
		const TowerPolynomial	f,
		mpz_srcptr	n,
		const TowerPolynomial	g )

Definition at line 1375 of file dpoly.cpp.

{
  // We assume that m > 0. THIS IS NOT CHECKED!!
  mpz_t n;
  mpz_init_set(n, m);
  TowerPolynomial prod = from_long(level, 1);
  TowerPolynomial base = copy(level, f);
  TowerPolynomial tmp;
 
  for (;;)
    {
      //      fprintf(stdout, "prod = ");
      //      dpoly(level,prod);
      //      fprintf(stdout, "\nbase = ");
      //      dpoly(level,base);
      //      fprintf(stdout, "\n");
      if (RingZZ::mod_ui(n, 2) == 1)
        {
          tmp = mult(level, prod, base, false);
          remainder(level, tmp, g);
          // TODO: free prod
          prod = tmp;
        }
      mpz_tdiv_q_2exp(n, n, 1);
      if (mpz_sgn(n) == 0)
        {
          mpz_clear(n);
          //      fprintf(stdout, "final prod = ");
          //      dpoly(level,prod);
          //              fprintf(stdout, "\nbase = ");
          //              dpoly(level,base);
          //              fprintf(stdout, "\n");
          // TODO: free base
          return prod;
        }
      else
        {
          tmp = mult(level, base, base, false);
          remainder(level, tmp, g);
          // TODO: free base
          base = tmp;
        }
    }
}

References base, copy(), from_long(), RingZZ::mod_ui(), mult(), and remainder().

Referenced by lowerP().