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

Re: Adjacency matrix bug?

To: graphthing-discuss@xxxxxxxx
Subject: Re: Adjacency matrix bug?
From: "David Symonds" <dsymonds@xxxxxxxxx>
Date: Mon, 15 Oct 2007 21:47:23 +1000
Delivered-to: archiver@xxxxxxxx
Delivered-to: graphthing-discuss-outgoing@xxxxxxxx
Delivered-to: graphthing-discuss@xxxxxxxx
Delivery-date: Mon, 15 Oct 2007 07:47:31 -0400
Dkim-signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=beta; h=domainkey-signature:received:received:message-id:date:from:to:subject:in-reply-to:mime-version:content-type:content-transfer-encoding:content-disposition:references; bh=g2E4HCUfyfxwm1OdlBAv9yzmp//tgU2sIi4c7PNuvaM=; b=k5F2iPyiA9NpvoyZUAxA5lxufNUkN07n/1sGWPC8DB0uwylvRgF509Vkc7xGdG9UClmL0oPmf5DPefqtppGqS/lhxC1/et1N4EwyKbDX3DHpRGVQKKaic52w78XejeL4tv6BLsfWaZBPvG9IpV8gRvIS+NNao3of8Dtzv9yA8J4=
Domainkey-signature: a=rsa-sha1; c=nofws; d=gmail.com; s=beta; h=received:message-id:date:from:to:subject:in-reply-to:mime-version:content-type:content-transfer-encoding:content-disposition:references; b=X3u7TBiHOId0wYS/oTbB6gOrILDKfHI/v7aHHmdunceKqT0pHMybJSC3HGbqtLHWaD9cKtayqHUB9xqxKQOoy3jvNDUPZsTOF2OwUtyQoawcoGOAJj3PL30OVD+v4VmMidq/tioKR9NUtF2GmHnPhIk/unH+4T1X0vPtOEoROyo=
In-reply-to: <20071015091427.GA19361@xxxxxxxxxxxxxxxxxxxxxxx>
References: <20071015091427.GA19361@xxxxxxxxxxxxxxxxxxxxxxx>
Reply-to: graphthing-discuss@xxxxxxxx
Sender: owner-graphthing-discuss@xxxxxxxx

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!

Dave.

References:
- Adjacency matrix bug?
  - From: Cyril Brulebois

Prev by Author: Adjacency matrix bug?
Previous by thread: Adjacency matrix bug?
Index(es):
- Author
- Thread