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XPRSgetunbvec

Purpose
Returns the index vector which causes the primal simplex or dual simplex algorithm to determine that a matrix is primal or dual unbounded respectively.
Topic areas
Solution, LP
Synopsis
int XPRS_CC XPRSgetunbvec(XPRSprob prob, int *p_seq);
Arguments
prob 
The current problem.
p_seq 
Pointer to an integer where the vector causing the problem to be detected as being primal or dual unbounded will be returned. In the dual simplex case, the vector is the leaving row for which the dual simplex detected dual unboundedness. In the primal simplex case, the vector is the entering row p_seq (if p_seq is in the range 0 to ROWS -1) or column (variable) p_seq-ROWS- SPAREROWS (if p_seq is between ROWS+SPAREROWS and ROWS+SPAREROWS+ COLS -1) for which the primal simplex detected primal unboundedness.
Error value
91 
A current problem is not available.
Further information
When solving using the dual simplex method, if the problem is primal infeasible then XPRSgetunbvec returns the pivot row where dual unboundedness was detected. Also note that when solving using the dual simplex method, if the problem is primal unbounded then XPRSgetunbvec returns -1 since the problem is dual infeasible and not dual unbounded.
Related topics
XPRSgetinfeas, XPRSlpoptimize.

Parent Topic Console and Library Functions

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