[Dip] using generateInitVars()

[Matthew Galati]

It might be that your initial columns are "not effective". 

By default, DIP price-and-cut periodically removes columns that have not been "effective". Currently, this means non-basic columns with effectiveness count < 0 - where an effectiveness unit is defined as +1 or -1 for each price iteration where its reduced cost < epsilon (+), otherwise (-).

This is a strategy to keep the size of the master LP basis small. It is the same idea people use for cuts in branch-and-cut.

To see what is getting "compressed", you can turn up the debugging log levels, LogLevel=5, LogDebugLevel=5. Look for the function markers by searching on the word "compressColumns". Warning -- you will get A LOT of debug information.

To turn off this feature, in your parameter file, set CompressColumns=0 in the appropriate section -- [DECOMP] or [PRICE_AND_CUT].

Matt


> -----Original Message-----
> From: dip-bounces at list.coin-or.org [mailto:dip-bounces at list.coin-or.org]
> On Behalf Of Kipp Martin
> Sent: Monday, August 09, 2010 5:16 AM
> To: dip at list.coin-or.org
> Subject: [Dip] using generateInitVars()
> 
> Hi:
> 
> I  am using the generateInitVars(DecompVarList & initVars) method to
> generate columns for the initial restricted master. However, when I print
> out the restricted master upon termination, I do not see any columns in the
> restricted master with the same objective function coefficient values as the
> ones I put in using initVars.push_back.
> 
> Any idea what could be happening?
> 
> Thanks
> 
> 
> --
> Kipp Martin
> Professor of Operations Research
> and Computing Technology
> Booth School of Business
> University of Chicago
> 5807 South Woodlawn Avenue
> Chicago, IL 60637
> 773-702-7456
> kmartin at chicagobooth.edu
> http://www.chicagobooth.edu/faculty/bio.aspx?person_id=12825325568
> http://projects.coin-or.org/OS
> 
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