[Bug-glpk] [Fwd: possible bug in 4.52]

[Andrew Makhorin]

-------- Forwarded Message --------
From: Meketon, Marc <address@hidden>
To: address@hidden <address@hidden>
Subject: possible bug in 4.52
Date: Thu, 25 Jul 2013 12:31:54 -0500

Andrew, 

 

Last night I began to create an integer program for finding which days
to perform periodic maintenance.  The idea is to organize periodic
maintenance to reduce the number of times the item goes into maintenance
while not increasing the number of hours of total maintenance too much.
I am using the latest version of GUSEK with the 32-bit version 4.52 GLPK
build.

 

When solving the attached model, if

 

param MTCE_EVENTS_COST := 0.0;

 

then I get a solution.  Not the solution that I want, but at least it
gets a solution.

 

If that is changed to

 

param MTCE_EVENTS_COST := 0.01;

 

then the model does not solve.  Sometimes, I receive the message 

Assertion failed: piv1 != 0.0

Error detected in file ..\src\glpspx02.c at line 3026

>Exit code: 3    Time: 444.488

Since the assertion failed, it may be due to a bug in GLPK.

 

More often, for the same problem, I receive 

Error: unable to factorize the basis matrix (1)

Sorry, basis recovery procedure not implemented yet

ios_driver: unable to solve current LP relaxation; glp_simplex returned
5

+1664019: mip =     not found yet >=  2.855670500e+003        (11689;
536)

glp_intopt: cannot solve current LP relaxation

Time used:   270.0 secs

Memory used: 25.4 Mb (26609330 bytes)

>Exit code: 0    Time: 270.581

 

As a final note, I really wanted to add the constraint below, but when I
do the code reaches various instabilities and does not solve.

 

subject to total_bins: sum{d in DAYS} x[d] <= 215; 

 

[The “215” is a parameter that will vary]

 

-Marc




________________________________________________________________________
This e-mail and any attachments may be confidential or legally
privileged. If you received this message in error or are not the
intended recipient, you should destroy the e-mail message and any
attachments or copies, and you are prohibited from retaining,
distributing, disclosing or using any information contained herein.
Please inform us of the erroneous delivery by return e-mail. Thank you
for your cooperation.

AssertionFailedOutput.txt
Description: AssertionFailedOutput.txt

model.mod
Description: model.mod