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/* File assemble_gens.c */
#include "tc.h"
#include "tcyacc.h"
Void
tc_assemble_gens(tc_pvar)
struct tc_str_vars *tc_pvar;
{
#include "tc_void.h"
register Int k;
register Int ncol;
register Int i;
register Int gens;
register Int j;
/* note which group generators are involutory.
* set GEN_TO_COL(generator) =0 if non-involutory, =-1 if involutory.
*/
for (k = 1; k <= NDGEN; k++)
if (Gen_st[k].gen_inv == k)
GEN_TO_COL[k] = -1;
else
GEN_TO_COL[k] = 0;
/* allocate columns to the generators and inverses and note ncol.
* also set up the tables COL_TO_GEN and INV_TO_COL.
*/
ncol = 0;
if (NDGEN == 1)
{ ncol = 2;
INV_TO_COL[1] = 2; COL_TO_GEN[1] = 1;
COL_TO_GEN[2] = -1; GEN_TO_COL[1] = 1;
INV_TO_COL[2] = 1; GEN_TO_COL[-1] = 2;
} else
{ for (i = 1; i <= NDGEN; i++)
{ gens = GEN_TO_COL[i];
if (gens > 0)
continue;
else if (gens == 0)
/* non-involutary generator, allocate 2 columns in the coset table.
*/
{ ncol++;
INV_TO_COL[ncol] = ncol + 1;
COL_TO_GEN[ncol] = i; GEN_TO_COL[i] = ncol;
ncol++;
INV_TO_COL[ncol] = ncol - 1;
COL_TO_GEN[ncol] = -i; GEN_TO_COL[-i] = ncol;
}
/* involutary generator, allocate only 1 column in the coset table.
*/
else if (i != 1)
{ ncol++;
INV_TO_COL[ncol] = ncol; COL_TO_GEN[ncol] = i;
GEN_TO_COL[i] = ncol; GEN_TO_COL[-i] = ncol;
}
/* for coincidence processing we must have the first 2 columns of the
* coset table assigned to a non-involutory generator and its inverse or
* 2 involutory generators. find a non-involutory generator (if it
* exists).
*/
else
{ for (j = 1; j <= NDGEN; j++)
if (GEN_TO_COL[j] == 0)
/* swap the columns for involutory generator 1 and non-involutory
* generator j.
*/
{ ncol = 3;
INV_TO_COL[1] = 2; COL_TO_GEN[1] = j;
GEN_TO_COL[j] = 1; INV_TO_COL[2] = 1;
COL_TO_GEN[2] = -j; GEN_TO_COL[-j] = 2;
/* set up the information for involutory generator 1. */
INV_TO_COL[3] = 3; COL_TO_GEN[3] = 1;
GEN_TO_COL[1] = 3; GEN_TO_COL[-1] = 3;
break;
}
if (j > NDGEN)
/* all generators are involutary, allocate only 1 column in the coset table.
*/
{ ncol++;
INV_TO_COL[1] = 1; COL_TO_GEN[1] = 1;
GEN_TO_COL[1] = 1; GEN_TO_COL[-1] = 1;
}
}
} /* end of 'for (i = ...)' */
}
NCOL = ncol;
return;
}
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