Function Mprwalk

Singular/walk.cc:6389–6926

* THE PERTURBATION WALK ALGORITHM WITH RANDOM ELEMENT * *******************************************************/

 * THE PERTURBATION WALK ALGORITHM WITH RANDOM ELEMENT *
 *******************************************************/
ideal Mprwalk(ideal Go, intvec* orig_M, intvec* target_M, int weight_rad,
              int op_deg, int tp_deg, int nP, int reduction, int printout)
{
  BITSET save1 = si_opt_1; // save current options
  if(reduction == 0)
  {
    si_opt_1 &= (~Sy_bit(OPT_REDSB)); // no reduced Groebner basis
    si_opt_1 &= (~Sy_bit(OPT_REDTAIL)); // not tail reductions
  }
  Set_Error(FALSE);
  Overflow_Error = FALSE;
  //Print("// pSetm_Error = (%d)", ErrorCheck());
#ifdef TIME_TEST
  clock_t  tinput, tostd, tif=0, tstd=0, tlift=0, tred=0, tnw=0;
  xtextra=0;
  xtif=0; xtstd=0; xtlift=0; xtred=0; xtnw=0;
  tinput = clock();

  clock_t tim;
#endif
  nstep = 0;
  int i, ntwC=1, ntestw=1, nV = currRing->N; //polylength

  //check that weight radius is valid
  if(weight_rad < 0)
  {
    WerrorS("Invalid radius.\n");
    return NULL;
  }

  //check that perturbation degree is valid
  if(op_deg < 1 || tp_deg < 1 || op_deg > nV || tp_deg > nV)
  {
    WerrorS("Invalid perturbation degree.\n");
    return NULL;
  }

  BOOLEAN endwalks = FALSE;

  ideal Gomega, M, F, FF, G, Gomega1, Gomega2, M1,F1,Eresult,ssG;
  ring newRing, oldRing, TargetRing;
  intvec* iv_M;
  intvec* iv_M_dp;
  intvec* iv_M_lp;
  intvec* exivlp = Mivlp(nV);
  intvec* curr_weight = new intvec(nV);
  intvec* target_weight = new intvec(nV);
  for(i=0; i<nV; i++)
  {
    (*curr_weight)[i] = (*orig_M)[i];
    (*target_weight)[i] = (*target_M)[i];
  }
  intvec* orig_target = target_weight;
  intvec* pert_target_vector = target_weight;
  intvec* ivNull = new intvec(nV);
  intvec* iv_dp = MivUnit(nV);// define (1,1,...,1)
#ifndef BUCHBERGER_ALG
  intvec* hilb_func;