[Bug-glpk] [Fwd: Bug with objective value]

[Andrew Makhorin]

-------- Forwarded Message --------
From: Dominik Hollmann <address@hidden>
To: address@hidden <address@hidden>
Subject: Bug with objective value
Date: Tue, 27 Oct 2015 09:25:43 +0000

Hi,

 

I might have found a bug when displaying the objective value after
solving a problem.

 

I am using GLPK 4.56 compiled as w64 command line application and
solving the attached model using the command „glpsol –m test.mod –o
test.sol“

 

In the mod-file there is a display command at line 179 „display
OOBJ_MDemSho;“ which gives -1481981.40399653. However, this is not the
correct objective value – which would be -3.565219231e-010 (or 0). In
line 180, there is a display command with the term of the objective,
which gives the correct result.

 

Also, in the sol-file you see both values: In line 6 it says “Objective:
OOBJ_MDemSho = -3.565219231e-010 (MINimum)” and in line 10 it states “
1 OOBJ_MDemSho B  -1.48198e+006                             “

 

One possible explanation might be, that primal and dual value of the
objective are mixed up. However, GLPK gives the same result with both
simplex algorithms as well as the interior point algorithm.

 

Could you have a look into this matter?

 

 

Kind regards

Dominik Hollmann

________________________________________

Dr. Dominik Hollmann

Senior Consultant

 

ORCONOMY GmbH 

Technologiepark 19

33100 Paderborn

 

Telefon +49 5251 68220-25

Mobil +49151 65119039

Fax +49 5251 68220-925

address@hidden

 

www.orconomy.de

________________________________________

 

ORCONOMY GmbH, Paderborn - HRB 9404, Amtsgericht Paderborn -
Geschäftsführer: Dr. Stefan Bunte, Dr. Jens Peter Kempkes, Dr. Ingmar
Steinzen

test.mod
Description: test.mod