Reach two different answers in two different versions of GAMS

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Lucas
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Reach two different answers in two different versions of GAMS

Post by Lucas » 3 weeks ago

Hi all,

I solved a model with two different versions of GAMS. (Version 24.2 and Version 27.3)

The answers I get from Version 24.2 are different from the answers from Version 27.3 !
Is this normal?


Thanks!

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Renger
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Re: Reach two different answers in two different versions of GAMS

Post by Renger » 3 weeks ago

Hi
If you have a model that can have multiple solutions and use a non-global solver, this might be (but I am no solver expert) due to a newer version of the solver that leads due to changes in the solver to another local solution It also depends on what you call different. You can save the solution of one version of Gams as a savepoint and solve the model with the other version of Gams using the savepoint and iteration limit set to 0, to see if it is a just a different local optimum. It should with iteration limit set to 0 report an optimal solution.
Cheers
Renger
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Enjoy modeling even more: Read my blog on modeling at The lazy economist

Lucas
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Re: Reach two different answers in two different versions of GAMS

Post by Lucas » 3 weeks ago

Dear Renger,
The model status is optimal in both versions, and The fixed answer is also feasible.
Thanks for the detailed and informative answer ;)

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