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

From: Andrew Makhorin
Subject: [Bug-glpk] [Fwd: possible bug in 4.52]
Date: Fri, 26 Jul 2013 13:37:45 +0400

-------- 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



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


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

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

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]



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Attachment: AssertionFailedOutput.txt
Description: AssertionFailedOutput.txt

Attachment: model.mod
Description: model.mod

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