Lovasz()

bool LLLoperations::Lovasz ( MutableMatrix * lambda, int k, ring_elem alphaTop, ring_elem alphaBottom )

staticprivate

Definition at line 72 of file LLL.cpp.

{
  // Test:alphaBottom * (D#(k-2) * D#k + lambda#(k,k-1)^2) <
  //              alphaTop * D#(k-1)^2
  ring_elem D2, D1, D, L;
  mpz_t a, b;
  lambda->get_entry(k - 1, k - 1, D1);
  lambda->get_entry(k, k, D);
  bool Lnotzero = lambda->get_entry(k - 1, k, L);
  if (k == 1)
    mpz_init_set(a, D.get_mpz());
  else
    {
      mpz_init(a);
      lambda->get_entry(k - 2, k - 2, D2);
      mpz_mul(a, D2.get_mpz(), D.get_mpz());
    }
  mpz_init(b);
  if (Lnotzero)
    {
      mpz_mul(b, L.get_mpz(), L.get_mpz());
      mpz_add(a, a, b);
    }
  mpz_mul(a, a, alphaBottom.get_mpz());  // This is the LHS.
 
  mpz_mul(b, D1.get_mpz(), D1.get_mpz());
  mpz_mul(b, alphaTop.get_mpz(), b);  // RHS
  int cmp = mpz_cmp(a, b);
  mpz_clear(a);
  mpz_clear(b);
  return (cmp < 0);
}

References MutableMatrix::get_entry(), and ring_elem::get_mpz().

Referenced by doLLL().