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nautyex1.c
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nautyex1.c
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/* This program prints generators for the automorphism group of an
n-vertex polygon, where n is a number supplied by the user.
This version uses a fixed limit for MAXN.
*/
#define MAXN 1000 /* Define this before including nauty.h */
#include "nauty.h" /* which includes <stdio.h> and other system files */
int
main(int argc, char *argv[])
{
graph g[MAXN*MAXM];
int lab[MAXN],ptn[MAXN],orbits[MAXN];
static DEFAULTOPTIONS_GRAPH(options);
statsblk stats;
int n,m,v;
/* Default options are set by the DEFAULTOPTIONS_GRAPH macro above.
Here we change those options that we want to be different from the
defaults. writeautoms=TRUE causes automorphisms to be written. */
options.writeautoms = TRUE;
while (1)
{
printf("\nenter n : ");
if (scanf("%d",&n) != 1 || n <= 0) /* Exit if EOF or bad number */
break;
if (n > MAXN)
{
printf("n must be in the range 1..%d\n",MAXN);
exit(1);
}
/* The nauty parameter m is a value such that an array of
m setwords is sufficient to hold n bits. The type setword
is defined in nauty.h. The number of bits in a setword is
WORDSIZE, which is 16, 32 or 64. Here we calculate
m = ceiling(n/WORDSIZE). */
m = SETWORDSNEEDED(n);
/* The following optional call verifies that we are linking
to compatible versions of the nauty routines. */
nauty_check(WORDSIZE,m,n,NAUTYVERSIONID);
/* Now we create the cycle. First we zero the graph, than for
each v, we add the edge (v,v+1), where values are mod n. */
EMPTYGRAPH(g,m,n);
for (v = 0; v < n; ++v) ADDONEEDGE(g,v,(v+1)%n,m);
printf("Generators for Aut(C[%d]):\n",n);
/* Since we are not requiring a canonical labelling, the last
parameter to densenauty() is not required and can be NULL. */
densenauty(g,lab,ptn,orbits,&options,&stats,m,n,NULL);
/* The size of the group is returned in stats.grpsize1 and
stats.grpsize2. */
printf("Automorphism group size = ");
writegroupsize(stdout,stats.grpsize1,stats.grpsize2);
printf("\n");
}
exit(0);
}

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