[Coin-osi-devel] Turning presolve off with OsiXpr

[Francois Margot]

On Mon, 12 Jun 2006, Matthew Saltzman wrote:

> On Mon, 12 Jun 2006, Francois Margot wrote:
>
>> 
>> How do I get Xpress to turn off preprocessing? I use:
>> 
>>    si->setHintParam(OsiDoPresolveInInitial, false, OsiForceDo);
>> 
>> where si is a pointer to an OsiXprSolverInterface object.
>> But this has no effect, apparently. I can not find a
>> setHintParam() method in OsiXprSolverInterface. Is this missing
>> or does the code in OsiSolverInterface::setHintParam be enough?
>
> Most SIs (XPRESS included) don't respect hints.  The most straightforward 
> thing is to hook the problem object and call the appropriate XPRESS function 
> directly.  Unfortunately, it looks like the current XPRESS implementation 
> doesn't support that directly.
>
> You want something akin to The OsiCpx getEnvironmentPtr().  I'd implement it, 
> but I no longer have an XPRESS license.  If you would like to, it would be 
> appreciated.
>

I want to have a code without dynamic casts, working for all solvers.
Can I implement OsiXprSolverInterface::setHintParam() similarly to
what is done for Clp? I can make it work for presolve, and for the 
other hints the situation will not be worse than what it is now,
as far as I understand.

Francois