REDI()

void LLLoperations::REDI ( int k, int ell, MutableMatrix * A, MutableMatrix * Achange, MutableMatrix * lambda )

staticprivate

Definition at line 108 of file LLL.cpp.

{
  // set q = ...
  // negate q.
  ring_elem Dl, mkl, q;
  if (!lambda->get_entry(ell, k, mkl)) return;
  lambda->get_entry(ell, ell, Dl);
  mpz_srcptr a = mkl.get_mpz();
  mpz_srcptr b = Dl.get_mpz();  // b = D#ell
  mpz_t c, d;
  mpz_init(c);
  mpz_init(d);
  mpz_mul_2exp(c, a, 1);  // c = 2*lambda#(k,ell)
  mpz_abs(d, c);          // d = abs(2*lambda#(k,ell)
  mpz_add(c, c, b);       // c = 2*lambda#(k,ell) + D#ell
  mpz_mul_2exp(d, b, 1);  // d = 2*D#ell
  mpz_fdiv_q(c, c, d);    // c = (almost) final q
  mpz_neg(c, c);
  q = ring_elem(c);
 
  // A->addColumnMultiple(ell,q,k);
  // lambda->addColumnMultiple(ell,q,k);
 
  A->column_op(k, q, ell);
  if (Achange) Achange->column_op(k, q, ell);
  lambda->column_op(k, q, ell);
 
  mpz_clear(c);
  mpz_clear(d);
}

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

Referenced by doLLL().