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XPRSgetunbvec

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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.

Synopsis

int XPRS_CC XPRSgetunbvec(XPRSprob prob, int *junb);

Arguments

prob

The current problem.

junb

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 junb (if junb is in the range 0 to ROWS-1) or column (variable) junb-ROWS-SPAREROWS (if junb 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, XPRSmaxim and XPRSminim.

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