[Nauty-list] permutation matrix output
Brendan McKay
bdm at cs.anu.edu.au
Tue May 25 23:31:49 EST 2010
There isn't any built-in way to do that. If you are calling
nauty from your own program, you can do it by writing a
procedure that prints a permutation as a matrix then passing
that procedure to nauty in the useautomproc field of the
options argument (all in the manual). The procedure would
look like this:
void
writeautomasmatrix(int count, int *perm, int *orbits,
int numorbits, int stabvertex, int n)
{
// code here to write the permutation perm[0..n-1] as
// a permutation matrix. ignore the other arguments.
}
Brendan.
* Adam Bohn <mrbohn1 at yahoo.co.uk> [100525 21:35]:
> Hi,
>
> I am trying to find automorphisms of graphs in the form of
> permutation matrices. Specifically, I am looking at directed graphs,
> and would like the output to be of the form of an n x n matrix, where n
> is the number of edges of the graph, and the (i,j) entry is 1 if edge i
> is mapped to edge j with the same direction, and -1 if i is mapped to j
> with a change of direction.
>
> I have read through the nauty manual
> and cannot find any reference to computing automorphisms in the form of
> permutation matrices. Does anybody know if this is possible, or
> whether there is another program with this functionality?
>
> Thanks for any help.
>
> Adam.
>
>
>
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