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GAP 4.8.9 installation with standard packages -- copy to your CoCalc project to get it

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/****************************************************************************

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**

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*A  collect_relations.c         ANUPQ source                   Eamonn O'Brien

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**

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*Y  Copyright 1995-2001,  Lehrstuhl D fuer Mathematik,  RWTH Aachen,  Germany

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*Y  Copyright 1995-2001,  School of Mathematical Sciences, ANU,     Australia

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**

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*/

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#include "pq_defs.h"

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#include "pcp_vars.h"

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#include "pq_functions.h"

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/* collect defining relations and solve corresponding equations;

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   a commutator relation is stored with a negative length */

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void collect_relations(struct pcp_vars *pcp)

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{

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   register int *y = y_address;

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   register int i;

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   register int j;

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   register int k;

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   register int p1;

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   register int length;

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   register int cp, cp1, cp2;

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   register int relp = pcp->relp;

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   register int ndrel = pcp->ndrel;

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   register int lastg = pcp->lastg;

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   for (i = 1; i <= ndrel; ++i) {

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      /* space is required for two collected parts set up here

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         and possibly for 5 * pcp->lastg in collect_def_comm */

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      if (is_space_exhausted(7 * lastg + 7, pcp))

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         return;

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      cp1 = pcp->lused;

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      cp2 = cp1 + lastg;

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      /*  original zero out -- bug reported by John Cannon October 1998 */

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      /*

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            for (j = 1; j <= lastg; ++j)

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               y[cp1 + j] = y[cp2 + j] = 0;

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      */

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      for (j = 1; j <= 2; ++j) {

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         p1 = y[++relp];

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         if (p1 != 0) {

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            cp = (j == 1) ? cp1 : cp2;

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            /* bug fix */

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            for (k = 1; k <= lastg; ++k)

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               y[cp + k] = 0;

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            length = y[p1];

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            /* is the relation a word or a commutator? */

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            if (length > 0)

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               collect_gen_word(p1, length, cp, pcp);

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            else if (length < 0) {

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               /* we may need to update pcp->lused, as space immediately

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                  above it is used in commutator routines */

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               if (j == 2)

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                  pcp->lused += lastg;

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               collect_def_comm(p1, cp, pcp);

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               if (j == 2)

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                  pcp->lused -= lastg;

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            }

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            if (!pcp->valid)

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               return;

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         }

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      }

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      echelon(pcp);

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      if ((pcp->fullop && pcp->eliminate_flag) || pcp->diagn)

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         text(1, i, 0, 0, 0);

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      if (pcp->overflow || pcp->complete != 0)

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         return;

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   }

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}

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