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Re: [Help-glpk] Mir cut generation performance improvement

From: Andrew Makhorin
Subject: Re: [Help-glpk] Mir cut generation performance improvement
Date: Mon, 29 Feb 2016 11:57:22 +0300

> I noticed that mir cut generation takes considerable time on some
> large problems (like rocII-4-11 from miplib). The attached patch makes
> two improvements that considerably improve performance in such
> instances:
> 1. A lot of time was spent on generating a temporary vector in
> function aggregate_row. It is a lot faster to reuse an existing
> vector.
> 2. A search for an element in the same function was done in row order,
> where using the elements in the order they are in the column is more
> efficient. This changes the generated cuts in some cases, but seems
> neutral overall (0.3% less cuts in a test set of 64 miplib instances).

Patched. Please see the attachment.

Andrew Makhorin

Attachment: glpios06.c.gz
Description: GNU Zip compressed data

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