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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_word.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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#include "constants.h"

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#include "word_types.h"

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/* collect word in pcp generators of group; word has base address ptr;

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   set up the result as exponent vector with base address cp */

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void collect_word(int ptr, int cp, struct pcp_vars *pcp)

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{

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   register int *y = y_address;

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   int temp;

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   int gen, exp;

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   register int i;

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   register int lastg = pcp->lastg;

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   register int length = y[ptr];

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   /* zero out lastg entries in array in order to store result */

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

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      y[cp + i] = 0;

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   /* collect the word */

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   for (i = 2; i <= length; ++i) {

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      if ((gen = y[ptr + i]) > 0)

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         collect(gen, cp, pcp);

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      else

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         invert_generator(-gen, 1, cp, pcp);

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   }

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   /* now calculate the appropriate power of the collected part */

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   if ((exp = y[ptr + 1]) != 1) {

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      temp = ptr + y[ptr] + 1;

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      calculate_power(exp, temp, cp, pcp);

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   }

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}

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/* calculate the exp power of word stored as exponent-vector at cp;

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   ptr is index of free position for temporary storage in y */

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void calculate_power(int exp, int ptr, int cp, 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 lastg = pcp->lastg;

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   power(abs(exp), cp, pcp);

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   /* if necessary, calculate the inverse */

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   if (exp < 0) {

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      ++ptr;

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      vector_to_word(cp, ptr, pcp);

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

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         y[cp + i] = 0;

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      invert_word(ptr, cp, pcp);

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   }

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}

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/* collect a word in pcp generators which may be already stored

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   or is read in as string with base address ptr; store the result

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   as an exponent vector at cp; convert exponent vector

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   to string with base address ptr; and print out result */

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void setup_word_to_collect(

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    FILE *file, int format, int type, int cp, struct pcp_vars *pcp)

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{

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   int disp = pcp->lastg + 2;

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   register int ptr;

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   ptr = pcp->lused + 1 + disp;

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   if (type != FIRST_ENTRY && type != NEXT_ENTRY) {

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      if (format == BASIC)

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         read_word(file, disp, type, pcp);

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      else

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         pretty_read_word(file, disp, type, pcp);

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   }

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   collect_word(ptr, cp, pcp);

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   if (type == VALUE_A || type == VALUE_B || file != stdin)

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      return;

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   setup_word_to_print("result of collection", cp, ptr, pcp);

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}

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