[PPL-devel] [GIT] ppl/ppl(pip): Added a standalone PIP solver demo program.

[François Galea]

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.