Sven Verdoolaege a écrit :
On Wed, Oct 28, 2009 at 03:56:36PM +0100, François Galea wrote:
Though, it seems the example problems in piplib are revealing a(nother) flaw in the solver. I am currently investigating about this.
OK, please let me know when you have fixed this problem.
I just fixed a trivial bug in the parser, for files which do not have parameters but have one context matrix row. This helps reading (and solving) some of piplib's examples. I still find at least one problem file which causes trouble (
However, some results I found are different from those which are in the corresponding '.ll' solution files. For instance, in 'boulet.pip', I get the solution minimum {0 ; 0 ; 0}, since all constraints have a nonnegative constant term. PIPlib finds a solution with negative elements : "if (p>=-5) then {-3*p-15 ; -p-5 ; p+5}."
This may be valid if variables and parameters are not supposed nonnegative, but my current implementation of the solver does not support negative variables and parameters.
Hence the question: which result can be considered correct ?
Best, François.