[Osi] CPLEX Error 1217: No solution exists

[Laszlo Ladanyi]

No bug.

Pure and implemented means that if a derived class does not implement it then 
you get a compile time error. So it forces the user to think and implement 
something for the method. However, there is a default implementation, so the 
user can simply invoke the default implementation.

--Laci

On Mon, 2 Jun 2008, Matthew Galati wrote:

> Umm... ok, header has pure (=0) but src has it implemented. Bug.
>
>> It looks to me like base implementation is pure virtual
>>     /// Get objective function value
>>     virtual double getObjValue() const = 0;
>>
>>
>>
>>> CPLEX wipes out all solution information as soon as you make any
>>> change to the problem whatsoever. I don't believe that the objective
>>> value is one of the things cached in the base class. If you look at
>>> the current implementation of getObjVal() in OsiCpx, it tries to get
>>> the objective value using CPXgetobjval(). If Cplex reports
>>> CPXERR_NO_SOLN, then the function returns 0.0 by default. In the base
>>> class, the default implementation of the getObjVal() function computes
>>> the objective value on the fly from cached data, which I guess would
>>> fix the problem. Try just commenting out the getObjVal() function in
>>> OsiCpx or else call the base class implementation from there and see
>>> if that does what you need.  If that works, we should probably make
>>> that change.
>>>
>>> Cheers,
>>>
>>> Ted
>>>
>>>
>>>
>>> Matthew Galati wrote:
>>>
>>>> This might be related to an old discussion...
>>>>
>>>> Using OsiCpx, I do
>>>>   initialSolve()
>>>>   getObjValue()
>>>>   addCols()
>>>>   getObjValue()  --> returns CPLEX Error  1217: No solution exists
>>>>
>>>> This is just an LP. Earlier issues with caching seem to have to do
>>>> with switching from MIP to LP, etc.
>>>>
>>>> It looks like some attempt to keep cache was already made. Any ideas?
>>>> If needed, I can create a driver program to show this issue.
>>>>
>>>> int err = CPXaddcols(env_,
>>>> getLpPtr(OsiCpxSolverInterface::KEEPCACHED_ROW),
>>>>                       numcols, nz, const_cast<double*>(obj),
>>>>                       start, index, elem,
>>>>                       const_cast<double*>(collb),
>>>>                       const_cast<double*>(colub), NULL );
>>>>
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>>>
>>
>>
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