Re: [Help-glpk] [Fwd: memory]

[glpk xypron]

Hello Ronald,

memory consumption for GMPL preprocessing can be quite big,
please, check if you have enough RAM installed:
For Windows use the task manager, for Linux use command free.

For sparse matrices it is important how you do the modelling
in GMPL. The following article describes how to make use
of the sparsity in a model.
http://publib.boulder.ibm.com/infocenter/oplinfoc/v6r3/index.jsp?topic=%2Filog.odms.ide.help%2FContent%2FOptimization%2FDocumentation%2FOPL_Studio%2F_pubskel%2Fglobals%2Feclipse_and_xplatform%2Fps_opl520.html

GMPL preprocessing can be avoided completely by directly
accessing the GLPK library. Several language bindings are
available (C, Java, Python, Ruby), cf.
http://en.wikibooks.org/wiki/GLPK/Language_Bindings

Best regards

Xypron


> -------- Forwarded Message --------
> Subject: memory
> Date: Thu, 24 Nov 2011 09:44:57 -0500
> 
> Hello,
> 
> I'm using GLPK in combination with CMPL and I encounter some issues with 
> the time required for preprocessing. My problem has 2N^2 rows and 2N^4 
> columns (real variables, less than 1% non-zeros). When I run the problem 
> for N=15 (450 rows, 101250 columns), the preprocessing takes 
> approximately 1 minute and the solver 3 seconds, which is great. When I 
> use N=30 instead (1800 rows, 1,620,000 columns) , the solving time goes 
> up to a few minutes, which is still great, but the preprocessing time 
> explodes to something like 9 hours. Although the problem is fairly 
> large, this increase seems stronger than expected. Is there a way I 
> could reduce the preprocessing time, e.g. by allocating more memory to 
> the program?
> 
> Many thanks,
> 
> Ronald
> 
> 
> 
> 
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> Help-glpk mailing list
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