Originally posted by: simon07

Hi all,

please excuse my poor english,
I am trying to solve a miqcp using ILOG CPLEX.
This is a part of the GAMS.log I copied in here:

• Generating MIQCP model zone_definition
• zone_definition_hajj.gms(87) 1101 Mb
• 552,802 rows 5,375,833 columns 24,407,560 non-zeroes
• 13,796 nl-code 152 nl-non-zeroes
• 5,369,472 discrete-columns
• zone_definition_hajj.gms(87) 1099 Mb
• Qmaker Time=17,172ms
• Executing CPLEX: elapsed 0:31:53.469
• zone_definition_hajj.gms(87) 1099 Mb

IBM ILOG CPLEX Jul 4, 2010 23.5.1 WIN 18414.18495 VS8 x86/MS Windows
Cplex 12.2.0.0, GAMS Link 34
GAMS/Cplex licensed for continuous and discrete problems.

Reading parameter(s) from "E:\Eigene Dateien\gamsdir\projdir\cplex.opt"
>> nodefileind=2
>> workdir=.D:\
Finished reading from "E:\Eigene Dateien\gamsdir\projdir\cplex.opt"
Reading data...
Starting Cplex...
Presolve time = 0.17 sec.
CPLEX Error 1001: Out of memory.
MIQP status(0):

• CPLEX Error 1001: Out of memory.

So what makes me wondering is the fact that the error message immediately
comes with starting cplex. And all i was able to find about that problem
deals with that error message at later point of excecution/solving.

Please also recognize that I am a really beginner in this topic.

Greetings
Simon from Germany
#CPLEXOptimizers
#DecisionOptimization

Originally posted by: SystemAdmin

Hi Simon from Germany,

looks like your problem is so big that CPLEX can't even start to work on it. There are several things you/can should try:

• export the problem to a .sav file and see how far you can get using the interactive optimizer. I don't know how GAMS runs CPLEX but it might be run in the same process which means that GAMS may eat some memory CPLEX needs.
• Enable the memory emphasis parameter.
• If you have a smaller data-set available then first try to use that smaller set to validate your code.

Unfortunately, I don't know how to export a model or set CPLEX parameters from GAMS but it should be documented somewhere. From you message I would guess that you can perform parameter settings in the file cplex.opt?
If the memory emphasis does not help there are other things that can be disabled but you should first try that.

Daniel (also from Germany)
#CPLEXOptimizers
#DecisionOptimization