Bug in Polymake

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mws
Posts: 32
Joined: 16 Jan 2014, 22:57

Bug in Polymake

Postby mws » 24 Jun 2014, 13:06

I am using Polymake 2.13-1 on Debian Linux, and I downloaded Paffenholz' database of Fano polytopes in dimension 4 from http://polymake.org/polytopes/paffenholz/www/fano.html.

When I start Polymake and do the following

$c = load("F.4D.0000.poly"); # this file just contains a single fano polytope

Polymake replies (how can I switch that off, by the way?)

polymake: validating XML file /home/mws/fano/5d/F.4D.0000.poly
polymake: XML validation succeeded

Printing the number of vertices, etc. seems to work fine. Now, if I continue with

$d = conv($c, scalar($c, -1));

and then give out the number of vertices, Polymake suffers a segmentation fault.

I attached the file for convenience.
Attachments
F.4D.0000.poly
(9.82 KiB) Downloaded 385 times

blorenz
Developer
Posts: 139
Joined: 10 Jan 2011, 17:21

Re: Bug in Polymake

Postby blorenz » 24 Jun 2014, 15:00

Hi,

first, to switch off the XML transformation you can set:

Code: Select all

$Verbose::files=0;
This works only for the current session, to make this setting permanent run:

Code: Select all

set_custom $Verbose::files=0;
Can you explain what you want to do, as

Code: Select all

conv( Polytope, Scalar )
does not make sense. The perl scalar function converts its argument to a perl scalar datatype, but conv expects an array of polytopes.


Also, I get an error message when trying to run this code:

Code: Select all

polytope > $c = load("F.4D.0000.poly"); polytope > $d = conv($c, scalar($c, -1)); polymake: ERROR: Useless use of a variable in void context at input line 1.
Ben

blorenz
Developer
Posts: 139
Joined: 10 Jan 2011, 17:21

Re: Bug in Polymake

Postby blorenz » 24 Jun 2014, 15:09

Probably you want to use scale instead of scalar:

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polytope > $d = conv($c, scale($c,-1)); polytope > print $d->VERTICES; 1 1 0 -1 1 1 1 -6 -1 1 1 -5 0 -1 1 1 1 0 -1 -5 1 -1 0 1 -1 1 -1 6 1 -1 1 5 0 1 -1 1 -1 0 1 5

mws
Posts: 32
Joined: 16 Jan 2014, 22:57

Re: Bug in Polymake

Postby mws » 24 Jun 2014, 19:08

Indeed, I meant to write scale() instead of scalar(). This is also what I used in my original code.

Meanwhile I tested a few more things and installed Polymake on another system. It turns out that this "bug" cannot be reproduced on this new system and that my installation seems to be broken. I just wanted to record this here for the sake of completeness.

User avatar
gawrilow
Main Author
Posts: 423
Joined: 25 Dec 2010, 17:40

Re: Bug in Polymake

Postby gawrilow » 24 Jun 2014, 22:36

Hi,

first, to switch off the XML transformation you can set:

Code: Select all

$Verbose::files=0;
Well, that's a tad too optimistic expectation. The validation (not transformation) is performed always, whenever a data file is touched, this variable merely controls the visibility of the message.


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