On Thu, 20 Aug 2009, Sam Seaver wrote:
I'm using Flux Variability Analysis to understand how a metabolic network may change under different conditions. I'm using glpk, and for all of the reactions, I am able to get an objective value. For some of the reactions, glpk reports that the primal solution is unbounded because the dual solution is infeasible. However, the very same program still prints out an objective value, and not necessarily zero, or infinity. Furthermore, the objective value is reasonable.
Reasonable, but not optimal.
Firstly, I do not understand how LP can calculate an objective value if it can prove that the primal solution is unbounded. Secondly, I would like to know, since the metabolic network is a published standard, how I can tackle the dual infeasibilities without making any changes to the network. Is it possible to use the objective values despite the dual infeasibilities, and whether I can or cannot, what should I say to an audience of bioengineers about these dual infeasibilities?
If the numbers represent something physical, unbounded is probably wrong. Your model probably needs fixing. -- Michael [email protected] "Pessimist: The glass is half empty. Optimist: The glass is half full. Engineer: The glass is twice as big as it needs to be." _______________________________________________ Help-glpk mailing list [email protected] http://lists.gnu.org/mailman/listinfo/help-glpk
