Forum Discussion
When does the LP status return problem status as "unsolved"?
Hi, I have an LP problem that does not find an optimal solution, but is also not infeasible or unbounded. The getparam("XPRS_LPSTATUS") query returns 7 (XPRS_LP_UNSOLVED). Any pointers as to why and...
XPRS_LP_UNSOLVED is the return status when the LP solver fails to solve your problem due to numerical difficulties. This can happen if you are solving your problem with the Barrier solver and it fails to converge to a feasible and optimal solution. Normally, crossover would still be able to clean up after such a Barrier solve, but if you turn crossover off, Xpress would return the XPRS_LP_UNSOLVED status instead.
If you post the output log from the Xpress-Optimizer, it should be clearer which algorithm was used and why it stopped with this status. In Mosel you enable output logging by calling setparam("XPRS_VERBOSE", true).