[FlopCpp] Slow problem generation

[Tim Hultberg]

I never looked much into the generation efficiency before, except for ensuring that generation time is proportional to 'nz' rather than 'm'*'n'.
Your problem shows the need to do this now. 

Some generation inefficiencies can be handled at modelling level, by substituting "such_that" by sparse subsets. But for sure there are also substantial optimizations possible within the library.

Yes, it would be great if you would look into this.

Also if you send me your model, it will help me to do this in parallel.

Cheers, Tim

(thanks for the nice words)


>>> "Tristram Gräbener" <tristramg at gmail.com> 06/06/2007 11:52 >>>
Hello,

I'm quite enthusiastic about FlopC++ as is pretty effective for modeling.

I'm trying to use it on a rather big problem (10'000 vars, 100'000
constraints, and should get bigger).
Currently it needs about 20 minutes to generate the problem and Cbc needs
only 15 to solve it, so it isn't as nice :)

I narrowed the problem down to  MP_constraint::coefficients(GenerateFunctor&
f) that take to much time.

Are you considering that problem, or is there even some improvement on that
? (I am using the trunk on the svn)

If no, I am will look into it - but I wanted to make sure that the has been
no work on it before.

Otherwise, thanks for that very nice library !

Regards,

Tristram