On Thursday, 29 October 2015 17:03:26 UTC-7, Dillon wrote: > > > Hi all, > > I thought I would start by asking the matroid group this non-matroidal > sage question, just in case I am missing something obvious. > > I set up a linear program: > > lp=MixedIntegerLinearProgram(maximization=True) > > Now I want to test whether lp has a feasible solution. Can I do this > without throwing an error? If there is no feasible solution, then > > lp.solve() > > produces an error: > > Traceback (click to the left of this block for traceback) > > sure, but there is Python's try: except: construction that makes it easy to deal with. And it is quite quick, too.
HTH, Dima > ... > sage.numerical.mip.MIPSolverException: 'GLPK : Solution is undefined' > > > I would like a command along the lines of lp.is_feasible(), but I can find no > trace of such a thing. lp.polyhedron() will return an empty polyhedron if the > lp is not feasible, but this is far too slow. I can get the error message > from lp.solve() in a fraction of second, but it takes minutes/hours for > lp.polyhedron() to tell me that the polyhedron is empty. > > > Does anyone know how to do this? Surely I am not the first person who wants > to run multiple linear programs in a row without knowing in advance that they > are feasible and without wanting to stop if they are not. > > > Thanks, > > > Dillon > > -- --- You received this message because you are subscribed to the Google Groups "sage-matroid" group. To unsubscribe from this group and stop receiving emails from it, send an email to [email protected]. For more options, visit https://groups.google.com/d/optout.
