[Nauty] Getting Started with Nauty

[Saul Spatz]

That's the version of nauty I have.  I must have been looking at a previous
User's Guide on line.  Is
http://users.cecs.anu.edu.au/~bdm/nauty/nug26.pdf
the most up to date?  I'll bookmark it.

Thanks for pointing this out.


On Thu, Apr 27, 2017 at 9:11 PM, Brendan McKay <Brendan.McKay at anu.edu.au>
wrote:

> Hi Saul.  Apparently you need to upgrade nauty.  gentreeg was there
> by the first non-beta release of version 2.6.  The current release is
> nauty26r7.  You can get it at:
>
> http://users.cecs.anu.edu.au/~bdm/nauty/
> http://pallini.di.uniroma1.it
>
> Brendan.
>
>
> On 28/4/17 11:55 am, Saul Spatz wrote:
>
> Thanks, Brendan.  It looks like I should have been using gentreeg from the
> beginning, but it doesn't seem to be mentioned in the User's Guide.
>
> On Thu, Apr 27, 2017 at 8:33 PM, Brendan McKay <Brendan.McKay at anu.edu.au>
> wrote:
>
>> Thanks Gordon.
>>
>> For larger sizes,  "gentreeg 10 | linegraphg"  will be more efficient.
>>
>> Saul: The reason your program crashed is that you can't convert
>> between the dense and sparse types just by casting the pointer type.
>> Casting pointers in C never changes the object which the pointer
>> points to.
>>
>> If you really need to do it inside a program, your choices are:
>>
>> (1) Write your own procedure to make the linegraph from the
>> dense graph structure that geng gives you.
>> (2) Use procedure nauty_to_sg, in the file nausparse.c, to convert
>> the dense graph to sparse format before calling linegraph().
>> (3) Use the OUTPROC feature in gentreeg, see the documentation
>> in gentreeg.c.  Note that it uses yet another data structure: one
>> designed to be as efficient as possible for trees.  From that you
>> can easily make the linegraph in some form convenient to you.
>>
>> Method (3) is the best option if you want to push the computation
>> as far as possible.
>>
>> Brendan.
>>
>> On 28/4/17 11:08 am, Gordon Royle wrote:
>>
>>> On the command line
>>>
>>> geng -c 10 9 | linegraphg
>>>
>>> does your job.
>>>
>>>
>>> On 28 Apr 2017, at 8:25 am, Saul Spatz <saul.spatz at gmail.com<mailto:s
>>> aul.spatz at gmail.com>> wrote:
>>>
>>> I'm a complete newbie.  I'm trying to write program that will call geng
>>> to
>>> generate trees of a given order and compute their line graphs.  I
>>> modified
>>> callgeng.c do construct the trees, and it ran successfully.  Since there
>>> doesn't seem to be a nauty function to compute the line graphs, I just
>>> copied the function linegraph from linegraphg.c.  Now my OUTPROC looks
>>> like:
>>>
>>> void OUTPROC(FILE *outfile, graph *g, int n)
>>> {    /* This will be called for each graph. */
>>>     ++counter;
>>>     sparsegraph h;
>>>     SG_INIT(h);
>>>     linegraph( (sparsegraph *) g, &h);
>>> }
>>>
>>> When I run the code, I get the error
>>>
>>> callgeng(30563,0x7fff7d2c9300) malloc: *** mach_vm_map(size=2251799813685
>>> 248)
>>> failed (error code=3)
>>> *** error: can't allocate region
>>>
>>> Apparently this occurs the first time the line
>>>     DYNALLOC1(size_t,eno,eno_sz,gnde,"linegraphg");
>>> is executed.  I have never called SG_INIT for g, because the example
>>> shows
>>> that OUTPROC takes a parameter of type graph*, so I have just cast the
>>> pointer to (sparsegraph*) when calling linegraph.
>>>
>>> Is this the source of the problem?  Is there a built-in way to construct
>>> a
>>> sparsegraph from a dense graph?
>>>
>>> Thanks for any assistance you can give me.
>>> _______________________________________________
>>> Nauty mailing list
>>> Nauty at anu.edu.au<mailto:Nauty at anu.edu.au>
>>> http://mailman.anu.edu.au/mailman/listinfo/nauty
>>>
>>> Gordon Royle
>>>
>>> School of Mathematics and Statistics
>>> University of Western Australia
>>>
>>> Email: gordon.royle at uwa.edu.au<mailto:gordon.royle at uwa.edu.au>
>>>
>>> (Note: my gordon at maths.uwa.edu.au<mailto:gordon at maths.uwa.edu.au>
>>> address is deprecated and will stop working soon.)
>>>
>>>
>>>
>>>
>>>
>>>
>>>
>>>
>>>
>>>
>>>
>>>
>>>
>>>
>>>
>>> _______________________________________________
>>> Nauty mailing list
>>> Nauty at anu.edu.au
>>> http://mailman.anu.edu.au/mailman/listinfo/nauty
>>>
>>
>>
>
>