[Author Prev][Author Next][Thread Prev][Thread Next][Author Index][Thread Index]

Re: Adjacency matrix bug?

On 15/10/2007, Cyril Brulebois <cyril.brulebois@xxxxxxxxxxxxxxxx> wrote:
> Hi,
> I've been reported that there could be a bug in the adjacency matrix. A
> math teacher reported that it looked like it is handled by GraphThing
> with swapped lines & columns.

There *is* a known bug when the adjacency matrix is raised to a high
enough power, due to integer overflow. I don't think there's any other
bugs in it -- there's varying conventions as to whether rows or
columns have the source vertex of digraph edges, but that's not a bug.

> He also wondered whether it is possible to have a loop on a vertex,
> which I'm unable to figure out right now, since GraphThing is currently
> broken in Debian — I've just noticed that, trying to reproduce the
> problem that teacher mentioned, and I'm working on it.

No, there's no support for loops or multiple edges. It was planned,
but obviously nothing has happened development-wise for a while now.
I'll take patches, of course!