[Osi] Problems with OsiXprSolverInterface and XPress 18.1

[Christian Plum]

 Hi All

Im working on a COIN based project, where I have implemented a model in
FLOPC++ and until now solved the model using CBC through the
OsiCbcSolverInterface, which has worked great.

I would like to pump up the speed of the computation, so Im trying to solve
the problem instances using the Xpress solver.

Unfortunately I am getting the following error:


> Xpress-Optimizer v18.10.00
> Hyper capacity, MIP (10 threads), Barrier (10 threads), Network, QP/MIQP
> (c) Copyright Dash Associates 1984-2007
>
> incrementInstanceCounter:: numInstances 0
> incrementInstanceCounter:: numInstances 1
> FlopCpp: Number of constraint blocks: 3
> FlopCpp: Number of individual constraints: 34
> FlopCpp: Number of variable blocks: 2
> FlopCpp: Number of individual variables: 48
> FlopCpp: Number of non-zeroes (including rhs): 106
> FlopCpp: Generation time: 7.922
> ERROR: XPRSglobal in line 92 error 32 occured
> Solution of first instance (x)
> 0 0 ERROR: XPRSgetmipsol in line 823 error 32 occured
>   -6.27744e+066
> 0 1   -6.27744e+066
> 0 2   -6.27744e+066
> 0 3   -6.27744e+066
> 1 0   -6.27744e+066
> 1 1   -6.27744e+066
> 1 2   -6.27744e+066
> 1 3   -6.27744e+066
> 2 0   -6.27744e+066
> 2 1   -6.27744e+066
> 2 2   -6.27744e+066
> 2 3   -6.27744e+066
> ...
>

The documentation of Xpress refers error 32 as:


> Subroutine not completed successfully, possibly due to invalid argument.


Which hasn't helped me much.. Im suspcting that OsiXprSolverInterface is for
an older version of XPress ? And that the problem format could have changed
?

I am cabable of solving simpler non-COIN based problems using Xpress.

Looking forward to your help!

/Christian
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