[Coin-lpsolver] A bug. Re: Coin-lpsolver Digest, Vol 34, Issue 9

[Gleb Belov]

Hello,

I use CLP 1.4.0 in a cut&price algorithm, i.e., column generation with 
cuts. In the following mps: 
http://www.math.tu-dresden.de/~belov/AFFconstr.mps, I started with a 
50x50 diagonal matrix and added columns and cuts interchangedly. After 
adding a column, I always executed primal. After adding a cut, I 
executed dual, then primal and tried to find new columns. Betwenn the 
two last constraints no columns were generated. The dual & primal 
methods were as well executed after adding the last cut. Now, when I 
check the solution, for the last constraint the sum on the left-hand 
side is -43.5 while it should be -44. Moreover, a variable with index 
980 is in the basis. It is obviously an internal slack for that row. 
But: its value is 0 in the Release compilation and 2e+218 in the Debug 
compilation!

Moreover, the function ClpModel::getRowUpper/Lower returns an array of 
zeros and ClpModel::matrix()->getCoef(i,j) always returns zero...

Best regards,
Gleb

-- 
Mit freundlichen Gruessen

G. Belov
----------------------------------------------------------------------
Dr. Gleb Belov                                Gleb.Belov at tu-dresden.de
Wiss. Assistent                   http://www.math.tu-dresden.de/~belov
Technische Universitaet Dresden                 Tel: +49 351 463 34186
Institut fuer Numerische Mathematik             Fax: +49 351 463 34268
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