Re: Infinite cycles

Hello Andrew,

The dual simplex method, techniques for a fast and stable implementation
/ Achim Koberstein
Paderborn, Univ., Diss., 2005
Dissertation (PhD)

describes on page 89 the possibility of numerical cycling due to the
Harris test:

http://digital.ub.uni-paderborn.de/hs/content/pageview/1508326

Wouldn't it be safer to change the default ratio test to --norelax.

See
https://pdfs.semanticscholar.org/2472/518346d657b8126d8ebe8657e2626dff5ef9.pdf
for ideas how to avoid cycling.

Best regards

Heinrich

On 01/11/2017 08:06 PM, Mathieu Dutour wrote:
> Thanks a lot!
> 
>   Mathieu
> 
> On 11 January 2017 at 19:52, Heinrich Schuchardt <[email protected]
> <mailto:[email protected]>> wrote:
> 
>     glpsol -m GLP_buggy.mod  --norelax
>     runs fine.
> 
>     glpsol -m GLP_buggy.mod
>     loops for ever.
> 
>     I tested with the GLPK 4.61 prerelease.
> 
>     Best regards
> 
>     Heinrich Schuchardt
> 
>     On 01/11/2017 12:14 PM, Mathieu Dutour wrote:
>     > Dear all,
>     >
>     > I obtained some infinite cycles when running the
>     > glpsol standalone solver on some instances.
>     > See two files in attachment.
>     >
>     > I had the instances of this phenomenon with
>     > version 4.57 which disappeared with version 4.60.
>     >
>     > Is there a way to avoid this phenomenon? I mean
>     > it is fully acceptable to me to have GLPK report
>     > that he cannot solve an instance due to numerical
>     > instability. What is not acceptable is the infinite
>     > cycles.
>     >
>     > Thanks in advance for any help.
>     > Sincerely,
>     >
>     >   Mathieu
>     >
>     >
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> 
>