> In my optimization work, I almost always use the > API of a solver instead of a modeling language. > The reason is that I usually want to solve another > problem related to the first and its solution. > Absent a reliable mechanism for converting variable > names to variable indices this can be difficult. > Being able to do the following from within code would be a good thing: > read a problem specified in a modeling language > solve problem > update problem > solve problem > rinse and repeat as necessary > print solution in convenient form. > > Being able to convert names to indices would facilitate > the update problem and print solution steps.
I encountered a similar problem, however, I cannot formalize that. Looks like there must be another, more complicated API level, which provides a more convenient indexing mechanism to access the variables and constraints. Cplex-like way to access variables/ constraints by their ordinal numbers is exhaustive, but it is not natural in most cases. As far as I know in OSL there was an attempt to resolve this issue by introducing so called "subproblems" (in terms of components of the constraint matrix). _______________________________________________ Help-glpk mailing list Help-glpk@gnu.org http://lists.gnu.org/mailman/listinfo/help-glpk