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Re: [Help-glpk] lp/mip preprocessor api

From: Andrew Makhorin
Subject: Re: [Help-glpk] lp/mip preprocessor api
Date: Sun, 03 Dec 2017 13:43:06 +0300

Hi Chris,

>         There is no need (and technically it'd be difficult) to load Q
>         back into
>         the PP wksp. It would be sufficient to provide some specific
>         preprocessor routines that allows, for example, fixing a
>         column or add a
>         row to the current instance residing in the workspace.
> If I understand correctly, currently glp_npp_build_prob() frees almost
> all problem data from the workspace, keeping only the references
> needed for glp_npp_load_sol() and glp_npp_recover_sol(). This is a
> reasonable design since in most cases there is no need to keep the
> additional data in the workspace. However this means that after
> calling glp_npp_build_prob() no further preprocessing can be done
> using the same workspace, and that glp_npp_build_prob() can only be
> called once.

Currently, yes, npp_build_prob removes that data from the workspace.
However on api level there will be a flag not to do that.

I think to implement an initial version of api and then to see what
needs to be added or improved.


Andrew Makhorin

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