[Top][All Lists]

[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index]

[Help-glpk] using lpp_presolve

From: Erik Rantapaa
Subject: [Help-glpk] using lpp_presolve
Date: Sun, 6 Jun 2004 16:22:01 -0700 (PDT)


I'd like to use use lpp_presolve to obtain a reduced set of constraints without
solving it. I then would like to output the constraints in terms of the
variable names.

For instance, given binary variables x and y, the constraint

s.t. x + y >= 2;

would yield x = 1, y = 1 along with the elimination of x and y in any other
constraints that involve them.

I've tried following the logic in simplex2() in file glplpx6a.c, but I'm
not sure what to do after something like:

    LPX* lp = original problem
    LPP *lpp = lpp_create_wksp();
    lpp_load_orig(lpp, lp);
    int ret = lpp_presolve(lpp);
    // check value of ret
    LPX *prob = lpp_build_prob(lpp);

The LPX data structure prob seems to have what I want, although I need to
map the structural variable names back to the ones used in lp.

Does anyone know what to do next?


Erik Rantapaa

Do you Yahoo!?
Friends.  Fun.  Try the all-new Yahoo! Messenger. 

reply via email to

[Prev in Thread] Current Thread [Next in Thread]