[Coin-discuss] OsiCpx use of CPXnewcols

[Brady Hunsaker]

Using CPLEX 9.0 recently, I had segfaults from building an instance 
using addRow.  I believe the problem was that new columns were being 
"added" as part of the addRow call, which uses the CPLEX function 
CPXaddrows.  The CPLEX 9.0 documentation says that "The use of 
CPXaddrows  as a way to add new columns is discouraged in favor of a 
direct call to CPXnewcols before calling CPXaddrows."

Given that I was getting segfaults, "discouraged" may not be the correct 
word.  Anyway, I modified my version of OsiCpxSolverInterface::addRow to 
use CPXnewcols first, as you can see in the attached file (which is just 
that one method).  Although this is not particularly efficient, it has 
run just fine on an instance with about 200,000 rows but only a few 
nonzeros in most rows.

I think that OsiCpx should be changed in the repository, but I'm not 
sure whether this issue affects earlier versions of CPLEX or whether 
there is a better approach.  I'd appreciate hearing from someone who has 
worked on OsiCpx.  Thanks,

Brady

-- 
Brady Hunsaker
Assistant Professor
Industrial Engineering
University of Pittsburgh
http://www.engr.pitt.edu/hunsaker/
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