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Re: [Bug-glpk] reading MPS files fails if tabs in comment


From: Andrew Makhorin
Subject: Re: [Bug-glpk] reading MPS files fails if tabs in comment
Date: Wed, 17 May 2006 08:53:03 +0400

> Reading an MPS file fails if any tabs (ASCII 0x09) are used, even in a
> comment.  This causes some MIPLIB files to fail reading.
> 
> A workaround is to use the --freemps option, even though the 
> non-commented part of the file conforms to the stricter format.
> 
> This could be corrected by changing the routine read_card in file 
> glplpx8a.c to ignore everything after a leading '*', similar to the way 
> it is already done in read_char in the same file.

In glpk 4.10 I changed the default option --mps to --freemps, because
most recent model collections (such as miplb 2003) are in free mps
format; besides, free mps is compatible with fixed mps except cases
when rhs, ranges, or bounds vector names are omitted (as in some old
models from netlib collection).

I think it is sufficient to use --freemps (or lpx_read_freemps) to
read most models in both fixed and free mps formats, and would not
like to change the routine lpx_read_mps which may be used to test if
a model conforms to the fixed mps format as defined in mps/360 (as
you remember in that package a model is a deck of 80-column punch
cards: http://en.wikipedia.org/wiki/Punch_card :)

Andrew Makhorin





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