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From: | Andrew Makhorin |
Subject: | Re: [Help-glpk] MIP Solvers (i.e CBC, CPLEX, GLPK, GUROBI, LPSOLVE, SCIPC, SCIPL, SCIPS and XPRESS) Benchmark |
Date: | Mon, 19 Nov 2012 12:41:21 +0400 |
> > Looks like your instance is maximization while mps always assumes > > minimization. You need either to change the objective sign in the > > mathprog model or specify --max option for glpsol. > > I don't understand this statement. Where do you "specify -max option > for glpsol"? > > e.g. glpsol --math TimberHarvestModel_0025p.mod --wfreemps > TimberHarvestM_freemps.mps > > The objective function of the MatProg model is already maximize. > > e.g. > > maximize Discounted_Net_Value: > sum {s in STAND, p in PERIOD} Stand_Cut_Candidates[s,p] * > NPV_Calc[s,p] * FStand[s,p]; > When you pass mps to glpsol, the optimization direction is minimization by default, so you need to specify the --max option to tell glpsol to maximize rather than minimize.
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