Infeaseability problem

GAMS
1

Hi GAMS users,
I’m starting to use gams.

I´m currently have the following problem:

I present a model for lot splitting and the problem is with the variable that represent the sublots “s”. It doesn´t calculate it.
It´s always zero, and that make the problem infeasible:
because the sum of the sublots doesn´t equal the big lot,

I checked a lot of times the model and I can´t find the key.
I have also tried with the “feasibility relaxation” of CPLEX but I couldn’t make it work properly…

The file .gms is attached.

Any suggestion or idea would be highly appreciated!!

Thank you

Daniel

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lot streaming.gms (5.97 KB)

2

Hi Daniel



Try to add the line ”Option Limrow=200;” before the solve statement. This will give you a complete equation listing. Then look at Eqlot4 in the equation listing: All you s-variables are set to zero, some of the multiple times. You have to fix this first – maybe there are other thing later. Again, the equation listing can be very useful.



Good luck



Arne


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Arne Stolbjerg Drud

ARKI Consulting & Development A/S

Bagsvaerdvej 246A, DK-2880 Bagsvaerd, Denmark

Phone: (+45) 44 49 03 23, Fax: (+45) 44 49 03 33, email: adrud@arki.dk



From: gamsworld@googlegroups.com [mailto:gamsworld@googlegroups.com] On Behalf Of danielrossit@hotmail.com
Sent: Friday, November 08, 2013 2:17 PM
To: gamsworld@googlegroups.com
Subject: Infeaseability problem



Hi GAMS users,

I’m starting to use gams.



I´m currently have the following problem:



I present a model for lot splitting and the problem is with the variable that represent the sublots “s”. It doesn´t calculate it.

It´s always zero, and that make the problem infeasible:

because the sum of the sublots doesn´t equal the big lot,



I checked a lot of times the model and I can´t find the key.

I have also tried with the “feasibility relaxation” of CPLEX but I couldn’t make it work properly…



The file .gms is attached.



Any suggestion or idea would be highly appreciated!!



Thank you



Daniel


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3

Thank you very much!!!
it has been REALLY helpful!!!

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