Returns the mapping of the row and column numbers from the presolve problem back to the original problem.

The following reads in a (Mixed) Integer Programming problem and gets the mapping for the rows and columns back to the original problem following optimization of the linear relaxation. The elimination operations of the presolve are turned off so that a one-to-one mapping between the presolve problem and the original problem.

XPRSreadprob(prob,"MyProb","");
XPRSsetintcontrol(prob,XPRS_PRESOLVEOPS,255);
XPRSmipoptimize(prob,"l");
XPRSgetintattrib(prob,XPRS_COLS,&cols);
colmap = malloc(cols*sizeof(int));
XPRSgetintattrib(prob,XPRS_ROWS,&rows);
rowmap = malloc(rows*sizeof(int));
XPRSgetpresolvemap(prob,rowmap,colmap);

The presolved problem can contain rows or columns that do not map to anything in the original problem. An example of this are cuts created during the MIP solve and temporarily added to the presolved problem. It is also possible that the presolver will introduce new rows or columns. For any row or column that does not have a mapping to a row or column in the original problem, the corresponding entry in the returned rowmap and colmap arrays will be -1.

Working with Presolve.