[Coin-discuss] no integers in writeMps?

[Matthew Saltzman]

On Thu, 3 Feb 2005, Brady Hunsaker wrote:

> John J Forrest wrote:
>> 
>> Brady,
>> 
>> CoinMpsIO does write integer information if integrality array set.  This is 
>> done automatically by OsiSolverInterface::writeMpsNative or can be done by 
>> CoinMpsIO::copyInIntegerInformation.  How do you want it to work?
>> 
>> John
>> 
>
> Thanks for the quick reply, John.
>
> I looked more carefully at the issue.  I'm using OsiCpx, and it turns out 
> that OsiCpx uses CPLEX's routine for writing MPS files, which for some reason 
> doesn't include the integrality information (perhaps it is relaxed?).  There 
> is a comment in OsiCpxSolverInterface.cpp indicating that this is a known 
> error.
>
> An easy solution would be to change the code to use CoinMpsIO, based on your 
> response.  I haven't tested this, but looking through the CoinMpsIO code, it 
> doesn't look like this output includes integer information either.  At least, 
> it doesn't appear to output "INTORG" and "INTEND" markers as I would expect. 
> Is it implemented in some other way?

writeMps() uses the extended bound type codes, so for example "BV" in the 
BOUNDS section indicates a binary variable.  There are other codes for 
other types of integers, but the type codes don't seem to be documented 
explicitly.  John must know them by heart, but a comment or two would help 
the rest of us out.  There's a massive cascading if-then starting around 
line 3619.

INTORG/INTEND and SOSORG/SOSEND are recognised on input, though.

 		Matt


>
> Brady
>
>
>> 
>> *Brady Hunsaker <hunsaker at engr.pitt.edu>*
>> Sent by: coin-discuss-bounces at list.coin-or.org
>> 
>> 02/02/2005 02:33 PM
>> Please respond to
>> Discussions about open source software for Operations Research 
>> 
>> 	To
>> 	coin-discuss at list.coin-or.org
>> cc
>> 	Subject
>> 	[Coin-discuss] no integers in writeMps?
>> 
>> 
>> 
>> 
>> 
>> 
>> 
>> It appears that Coin writeMps does not indicate integer variables.  Is
>> this correct?  Can we change that?
>> 
>> Brady
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-- 
 		Matthew Saltzman

Clemson University Math Sciences
mjs AT clemson DOT edu
http://www.math.clemson.edu/~mjs