bug-glpk
[Top][All Lists]
Advanced

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

[Bug-glpk] Bug in Dual/Reduced Cost computation for a simple lp


From: Anurag Jain
Subject: [Bug-glpk] Bug in Dual/Reduced Cost computation for a simple lp
Date: Fri, 29 Dec 2006 17:33:51 +0300

Hi Mao,

I am trying to use GLPK (version 4.13) to model a simple supply chain
network model to be solved as a linear program. The duals I am getting
for this linear program are not correct for a corner case (when demand
is equal to supply). I cross checked with cplex solver to see the
right dual/reduced costs for those variables and indeed cplex is
giving me the expected answer.

Please find attached the lp file (cplexlp.lp in cplex format) that you
can use with interactive cplex and glpsol both. The variables in
question are: Res1T1, Res1T2, Res1T3, Res1T4. The reduced costs of
these variables is not correct. Similarly the duals on rows Res1R1,
Res1R2, Res1R3, Res1R4 is also not correct. Please find attached the
solution files out of cplex (cplexsol.txt) and glpk 4.13 (glpsol.txt)
with this mail.

Use of correct duals and reduced costs is important for my project.
Please help! Lastly I do appreciate your work and effort for the
freeware implementation of a lp solver. This really is great work for
the open source community!

Thanks,
Anurag

Attachment: cplexlp.lp
Description: Text document

Attachment: cplexsol.txt
Description: Text document

Attachment: glpsol.txt
Description: Text document


reply via email to

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