[Cbc] Re: mps error (John J Forrest)

[Spring]

There is no problem in cbc solver, the problem was in my code.
I've another question for you.
I'm solving big MIP problem and I'm using cbc solver as a standalone application.
How can I set cbc parameters to improve solver performance? There is a manual or a tutorial for this? I should try to solve big Mip problem in a reasonable time
Thanks

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Today's Topics:

   1. Re: mps error (John J Forrest)


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Message: 1
Date: Mon, 24 Sep 2007 10:21:56 -0400
From: John J Forrest 
Subject: Re: [Cbc] mps error
Cc: cbc at list.coin-or.org
Message-ID:
 
Content-Type: text/plain; charset="us-ascii"

Thank you for sending me the mps file.

I am surprised that glpk had no problems solving the problem.

If you look at the mps file you sent you will see that row R0000092 is an 
equality row with rhs of 0.0 and one element, a +1 in column C0002992. 
C0002992 is fixed to 1in the bounds section so obviously the problem is 
infeasible as reported.

John Forrest



Spring  
Sent by: cbc-bounces at list.coin-or.org
09/21/2007 10:34 AM

To
cbc at list.coin-or.org
cc

Subject
[Cbc] mps error






Hi, 
I'm trying to solve a Binary optimization problem by using both coin-or 
cbc an glpk solver. In particular I'm using glpk to create the mps file 
for the problem and cbc to solve it.
My optimization problem is the following: I'have 30 cars and 374 park rows 
and I have to find the best parking.
I have choose to solve firstly the problem with 20 cars and all the park 
rows, I've obtained the solution and now I want to solve the problem with 
30 cars and all the rows by fixing to 1 the variables obtained like 
results with 20 cars but when I give the generated mps file to cbc I've 
the following error:
Model was imported from 
D:/workspace/OptimizationProject/info/optimizationFiles/F2cv_ProblemDescription.mps 
in 2.303 seconds
1 infeasibilities
Problem is infeasible - tightenPrimalBounds!

What's the problem?
I've solved in the same way the problem with Glpk and I've no errors.

Thanks
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