Originally posted by: chinaustin

Hi,

I am trying to solve an LP problem and it gives an saying " CPLEX Error 1258: No LU Factorization exists".

Can anybody tell be how to overcome this error?

Thanks for the help.
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Originally posted by: SystemAdmin

Can you please be a bit more specific on what you are doing? Which API are you using? Which commands and parameter settings?
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Originally posted by: SystemAdmin

The description of this error in the reference manual says:

The requested item requires the presence of factoring.
You may need to optimize with a 0 (zero) iteration limit to factor.

Does this help? If not then I agree with Tobias: you need to provide more details. What exactly are you doing? What is the function that produces this error?
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Originally posted by: J.Haas

Hi, 

I get the same error message when trying the cplex.getRangeSA.

I am solving an LP problem with Java. I don't really understand what "You may need to optimize with a 0 (zero) iteration limit to factor."  means.

 

Thanks for your help

 

 

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Originally posted by: TobiasAchterberg

The error message says that this operation can only be executed if there is a factorization of the current basis matrix resident in memory. If you have just solved your LP, this should be the case. But if you have applied problem modification methods afterwards, the factorization gets destroyed. If you still want to investigate the current basis, then you need to trigger a fresh factorization of the basis matrix. This can be done by setting the simplex iteration limit parameter to 0 and then solving the model again. It means that CPLEX will stop immediately (because it will hit the iteration limit), but still perform a fresh factorization of the current basis matrix.

 

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