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problem.storecuts

problem.storecuts

Purpose
Stores cuts into the cut pool, but does not apply them to the current node. These cuts must be explicitly loaded into the matrix using problem.loadcuts or problem.setbranchcuts before they become active.
Synopsis
problem.storecuts (nodupl, mtype, rtype, rhs, mstart, mindex, mcols, dmatval)
Arguments
nodupl 
0 
do not exclude duplicates from the cut pool;
1 
duplicates are to be excluded from the cut pool;
2 
duplicates are to be excluded from the cut pool, ignoring cut type.
mtype 
Array containing the cut types. The cut types can be any integer and are used to identify the cuts.
rtype 
Character array containing the row types:
L 
indicates a ≤ row;
E 
indicates an = row;
G 
indicates a ≥ row.
rhs 
Array containing the right hand side elements for the cuts.
mstart 
Array containing offsets into the mcols and dmtval arrays indicating the start of each cut. This array is of length ncuts+1 where ncuts is the length of drhs, with the last element mstart[ncuts] being where cut ncuts+1 would start.
mindex 
Array where the cuts will be returned.
mcols 
Array containing the column indices in the cuts.
dmatval 
Array containing the matrix values for the cuts.
Further information
1. storecuts can be used to eliminate duplicate cuts. If the nodupl parameter is set to 1, the cut pool will be checked for duplicate cuts with a cut type identical to the cuts being added. If a duplicate cut is found the new cut will only be added if its right hand side value makes the cut stronger. If the cut in the pool is weaker than the added cut it will be removed unless it has been applied to an active node of the tree. If nodupl is set to 2 the same test is carried out on all cuts, ignoring the cut type.
2. storecuts returns a list of the cuts added to the cut pool in the mindex array. If the cut is not added to the cut pool because a stronger cut exits a None will be returned. The mindex array can be passed directly to problem.loadcuts or problem.setbranchcuts to load the most recently stored cuts into the matrix.
3. The columns and elements of the cuts must be stored contiguously in the mcols and dmtval arrays passed to storecuts. The starting point of each cut must be stored in the mstart array. To determine the length of the final cut the mstart array must be of length ncuts+1 with the last element of this array containing where the cut ncuts+1 would start.
Related topics
problem.loadcuts problem.setbranchcuts, Section "Working with the cut manager" of the Xpress Optimizer reference manual.

Parent Topic Reference Manual