Re: [Help-glpk] Structural variables initial values

[Antonello Lobianco]

I upgraded to last version 4.19 but I am expecting lots of toubles using 
functions to modify the problem object..

That's what:
1) I build a MIP problem and solve it (that's fine)
2) I add a row and some cols with glp_add_rows() and glp_add_cols()
3) I solve the new MIP and I got the expected results
4) I revert the MIP back with glp_del_rows() and glp_del_cols()
5) I add for the second time a row and few cols
6) I try to solve the MIP again but I get the LPX_E_FAULT error. But if at 
this point I save the problem e.g. in the cplex language and then try to 
solve it with glpsol it gives me the correct results!
Where am I wrong ????

Antonello

On mercoledì 11 luglio 2007, Antonello Lobianco wrote:
> Hello.. I have on my model many agents that need to frequently solve a
> (relatively small) MIP problem.
>
> This problem change slightly from one solve() call to to the other, so I am
> wandering if I can pass the previous solved quantities as initial values.
>
> I am currently running my simulations creating and destroying every time 
> the glpk problems, but I am wandering if it is best to create them only the
> first time and destroy them at the end of the simulation.
> If I don't destroy the glpk problems, is glpk smart enought to take
> advantage of previously solved problems, even if in the maintime the
> structure of the matrix is slighty changed (eg. I added a row and/or a
> column) ??
>
> cheers,
>    Antonello



-- 
Antonello Lobianco
Università Politecnica delle Marche
Dipartimento di Economia
P.le Martelli, 8 - 60121 Ancona Italy
TEl: +39.071.2207106
FAX: +39.071.2207102
OpenDocument welcome