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XPRSstrongbranch

Purpose
Performs strong branching iterations on all specified bound changes. For each candidate bound change, XPRSstrongbranch performs dual simplex iterations starting from the current optimal solution of the base LP, and returns both the status and objective value reached after these iterations.
Topic area
Branching
Synopsis
int XPRS_CC XPRSstrongbranch(XPRSprob prob, const int nbounds, const int colind[], const char bndtype[], const double bndval[], const int iterlim, double objval[], int status[]);
Arguments
prob 
The current problem.
nbounds 
Number of bound changes to try.
colind 
Integer array of size nbounds containing the indices of the columns on which the bounds will change.
bndtype 
Character array of length nbounds indicating the type of bound to change:
U 
indicates change the upper bound;
L 
indicates change the lower bound;
B 
indicates change both bounds, i.e. fix the column.
bndval 
Double array of length nbounds giving the new bound values.
iterlim 
Maximum number of LP iterations to perform for each bound change.
objval 
Objective value of each LP after performing the strong branching iterations.
status 
Status of each LP after performing the strong branching iterations, as detailed for the LPSTATUS attribute.
Example
Suppose that the current LP relaxation has two integer columns (columns 0 and 1 which are fractionals at 0.3 and 1.5, respectively, and we want to perform strong branching in order to choose which to branch on. This could be done in the following way: 
int colind[] = { 0, 0, 1, 1 };
char bndtype[] = "LULU";
double bndval[] = {1, 0, 2, 1};
double objval[4];
int status[4];
...
XPRSstrongbranch(prob, 4, colind, bndtype, bndval, 1000,
                 objval, status);
Further information
1. This function currently does not apply to general nonlinear problems.
2. Prior to calling XPRSstrongbranch, the current LP problem must have been solved to optimality and an optimal basis must be available.

Parent Topic Console and Library Functions

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