Forum Discussion
Obtaining the variable values in a callback
In the XPRSoptNodeEvent callback, in order to separate valid inequalities, one must access the values of the variables. Let's say we want to obtain the values of XBRBvar[] myVarSubset. To my understa...
- Q1: The numbers returned by getColNum() are established when XPRBprob.loadMat() is invoked. If you do not modify your problem afterwards in any way, then the function should return the index of the variable in the matrix. Notice however that this index is unrelated to the order in which you create the XPRBvar instances. It is defined by the order in which variables are extracted in loadMat().
- Q2: In order to fetch a single solution value you can use XPRSprob.getLpSolVal. Depending on how many values you need to fetch, it may be faster to fetch the whole array in one shot, though.
- Q3: Once the solution process has started, the indices in the original model are not going to change. So it is safe to precompute the name/index mapping.