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Re: [Help-glpk] Condensing a sparse matrix by creating a subset of param

From: Meketon, Marc
Subject: Re: [Help-glpk] Condensing a sparse matrix by creating a subset of parameter data
Date: Thu, 31 Mar 2016 09:21:17 -0500

Note that eliminating nodes that are not used typically have no effect on the solution time and memory requirements of the mathematical program due to the ability of the pre-processor to quickly reduce the matrix. 

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On Mar 31, 2016, at 9:19 AM, Abhishek Shivakumar <address@hidden> wrote:



I have an lp model that produces an extremely sparse constraint matrix. I would like to reduce the number of non-zero entries in this matrix (make the matrix more dense). The main cause of this sparse-ness is the relation between two parameters. They can be seen as ‘arcs’ and ‘nodes: not all nodes have arcs between them. Is there a way to create a subset of parameter data from the sets ‘arcs’ and ‘nodes’ based on whether they are connected? I would then be able to apply constraints only for this subset. In other languages (such as python) such an operation is possible through nested conditional statements. Is there a similar/equivalent approach in glpk/GNU mathprog?





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