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Re: [Help-glpk] MPS Free format

From: Samik Raychaudhuri
Subject: Re: [Help-glpk] MPS Free format
Date: Mon, 12 Jul 2004 10:24:44 -0400
User-agent: Mozilla/5.0 (Windows; U; Windows NT 5.1; en-US; rv:1.7) Gecko/20040514

Yeah I did mean the free MPS format introduced in IBM OSL.
I found out that the Coin optimization suit's Clp also does this format change. I had to execute the following command:
        clp -keepname off -import a.mps -presolve off -export b.mps
Though it might not be used by many, I think it is useful. The problem I am dealing with has these long variable names which means something in the real world. It would have been great had Glpk solved the same input file. With so many standards around, it's always painful to maintain compatibility .. no doubt.

On 7/12/2004 10:00 AM, Andrew Makhorin wrote:

I was referring to the two types of MPS models: fixed format and free
format. In free format there are no restrictions on the names of the variables etc. GLPSOL supports the fixed format as of now, but I have problems in free format.

Do you mean "free MPS format" introduced in IBM OSL? Or something else?
There are many packages that allow deviations from the standard MPS/360
format (names longer than 8 chars, arbitrary filed positions, etc.).
Glpk supports only the standard MPS/360 format with no deviations. In
my opinion, there is no reason to provide glpk with "free MPS format",
because it is not widely used and because the MPS format itself is
highly inconvenient in all aspects. (I think it would be much better to
develop a GNU low-level format for coding lp/mip models. Not XML-based
one, of course. :+)

Andrew Makhorin

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