|
| From: | Gábor Csárdi |
| Subject: | Re: [igraph] Comparing large graphs |
| Date: | Wed, 5 Dec 2012 16:06:34 -0500 |
Sorry. I am using Gcc 4.6.3 on a Ubuntu 12.04.
Thanks,
Charles
On Wed, Dec 5, 2012 at 10:01 PM, Gábor Csárdi <address@hidden> wrote:
> Charles,
>
> what is your platform? OS, OS version, C compiler version? Anything else
> that you might think is needed to reproduce this?
>
> G.
>
>
> On Wed, Dec 5, 2012 at 3:44 PM, Charles Novaes de Santana
> <address@hidden> wrote:
>>
>> Just to explay why I think my problem with the "infinity" values:
>>
>> Because I tryied to debug my program and I got the following message:
>>
>> Program received signal SIGSEGV, Segmentation fault.
>> igraph_vector_fill (v=0xbffff6ac, e=inf) at vector.pmt:682
>> 682 *ptr = e;
>>
>> As the value received by function igraph_vector_fill is "e=inf" I
>> suppose it was my problem.
>>
>> Best,
>>
>> Charles
>>
>> On Wed, Dec 5, 2012 at 9:40 PM, Charles Novaes de Santana
>> <address@hidden> wrote:
>> > Thank you again, Tamás. You were absolutely right about my mistake in
>> > printing the matrix. I did a simple cast and my matrix operations
>> > worked fine.
>> >
>> > But I still have problems with the "infinity" given by the
>> > shortest_paths function. I did the function you suggested me (to
>> > replace all IGRAPH_INFINITY by zeros), but I have problems in the
>> > calculation of the shortest paths itself, before I have the
>> > opportunity to replace the "inifinity" by "zero".
>> >
>> > If you don't mind, I am sending attached to this message a small
>> > program with the part of my code where I got the error. And an example
>> > of a network I am studying. Maybe it is an error in the format of my
>> > network and I can not understand it yet. Or maybe it is because my
>> > network is very sparse.
>> >
>> > Thank you very much for your attention,
>> >
>> > Best,
>> >
>> > Charles
>> >
>> > /*SOURCE CODE*/
>> >
>> > #include<igraph.h>
>> >
>> > int main(void){
>> > igraph_t g1;
>> > igraph_matrix_t l1;
>> > igraph_vs_t vertices;
>> >
>> > int i,j;
>> > FILE *ifile1;
>> >
>> > /*Reading the network*/
>> > ifile1=fopen("./network.net", "r");
>> > if (ifile1==0) {return 10;}
>> > igraph_read_graph_pajek(&g1, ifile1);
>> > fclose(ifile1);
>> >
>> > /*Initializing the matrix l1 and the vector of vertices*/
>> >
>> > igraph_vs_all(&vertices);
>> > igraph_matrix_init(&l1, 0, 0);
>> >
>> > /*Calculating the shortest paths*/
>> >
>> > igraph_shortest_paths(&g1,&l1,vertices,vertices,IGRAPH_ALL);
>> >
>> > /*Desconstructors*/
>> > igraph_matrix_destroy(&l1);
>> > igraph_vs_destroy(&vertices);
>> > igraph_destroy(&g1);
>> > return;
>> > }
>> >
>> >
>> > igraph_matrix_destroy(&l1);
>> > igraph_vs_destroy(&vertices);
>> > igraph_destroy(&g1);
>> >
>> >
>> > On Wed, Dec 5, 2012 at 10:32 AM, Tamás Nepusz <address@hidden> wrote:
>> >>> First, I was wondering if Igraph considers IGRAPH_INFINITY as zero or
>> >>> as other value.
>> >> IGRAPH_INFINITY is infinity, period. It is there only to provide us
>> >> with a sort-of-platform-independent way to refer to infinity.
>> >>
>> >>> I am working with shortest-paths matrices and I would
>> >>> like the distance between two vertices that can not reach each other
>> >>> to be zero.
>> >> Well, you have to check all the cells in the matrix and if a cell is
>> >> equal to IGRAPH_INFINITY, you have to set it to zero.
>> >>
>> >>> (I tryied to do "igraph_matrix_scale(matrix,1./2)" and it gave
>> >>> me a zero-matrix).
>> >> Theoretically it should work; there is no limitation on
>> >> igraph_matrix_scale to work on integer values only. I have just tested it on
>> >> my machine and it worked for me, so I guess that the error is somewhere
>> >> else; for instance, in the way you print the values.
>> >>
>> >> Cheers,
>> >> --
>> >> T.
>> >>
>> >>
>> >> _______________________________________________
>> >> igraph-help mailing list
>> >> address@hidden
>> >> https://lists.nongnu.org/mailman/listinfo/igraph-help
>> >
>> >
>> >
>> > --
>> > Um axé! :)
>> >
>> > --
>> > Charles Novaes de Santana
>> > http://www.imedea.uib-csic.es/~charles
>> > PhD student - Global Change
>> > Laboratorio Internacional de Cambio Global
>> > Department of Global Change Research
>> > Instituto Mediterráneo de Estudios Avanzados(CSIC/UIB)
>> > Calle Miquel Marques 21, 07190
>> > Esporles - Islas Baleares - España
>> >
>> > Office phone - +34 971 610 896
>> > Cell phone - +34 660 207 940
>>
>>
>>
>> --
>> Um axé! :)
>>
>> --
>> Charles Novaes de Santana
>> http://www.imedea.uib-csic.es/~charles
>> PhD student - Global Change
>> Laboratorio Internacional de Cambio Global
>> Department of Global Change Research
>> Instituto Mediterráneo de Estudios Avanzados(CSIC/UIB)
>> Calle Miquel Marques 21, 07190
>> Esporles - Islas Baleares - España
>>
>> Office phone - +34 971 610 896
>> Cell phone - +34 660 207 940
>>
>> _______________________________________________
>> igraph-help mailing list
>> address@hidden
>> https://lists.nongnu.org/mailman/listinfo/igraph-help
>
>
>
>
> --
> Gabor Csardi <address@hidden> MTA KFKI RMKI
>
>
> _______________________________________________
> igraph-help mailing list
> address@hidden
> https://lists.nongnu.org/mailman/listinfo/igraph-help
>
--
Um axé! :)
--
Charles Novaes de Santana
http://www.imedea.uib-csic.es/~charles
PhD student - Global Change
Laboratorio Internacional de Cambio Global
Department of Global Change Research
Instituto Mediterráneo de Estudios Avanzados(CSIC/UIB)
Calle Miquel Marques 21, 07190
Esporles - Islas Baleares - España
Office phone - +34 971 610 896
Cell phone - +34 660 207 940
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