Originally posted by: gtoptimizer

Hey all,

I sometimes get a "CPLEX Error 1252: Optimal solution required." when I make a call to CPXstrongbranch. I tried increasing the itlim value to no avail.

I am not sure what this error implies. The official description for the error is "An optimal solution must exist before the requested operation can be performed.", but this seems absurd when it comes to CPXstrongbranch.

Has anyone encountered and solved this issue before? Can any CPLEX developers help with this?

Thanks!

Elias

Originally posted by: AnirudhSubramanyam

https://www.ibm.com/developerworks/community/forums/html/topic?id=77777777-0000-0000-0000-000014479565&ps=25

Originally posted by: gtoptimizer

Hey Anirudh, thanks for your reply.

I can't see how the thread you linked to is related to my question though.

Do you mind explaining what you had in mind a bit?

Elias

Originally posted by: RWunderling

As stated in the reference manual, strong branching requires that you start with "an LP has been solved and that the optimal solution is resident.", i.e. a solution status of CPX_STAT_OPTIMAL (or CPX_STAT_OPTIMAL_INFEAS).  Be sure to call CPXdualopt() or CPXprimalopt() to get an optimal solution before you call CPXstrongbranch().

Roland