XPRSgetprimalray
XPRSgetprimalray |
Purpose
Retrieves a primal ray (primal unbounded direction) for the current problem, if the problem is found to be unbounded.
Synopsis
int XPRS_CC XPRSgetprimalray(XPRSprob prob, double dray[], int *hasRay);
Arguments
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prob
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The current problem.
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dray
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Double array of length
COLS to hold the ray. May be NULL if not required.
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hasRay
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This variable will be set to 1 if the Optimizer is able to return a primal ray, 0 otherwise.
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Example
The following code tries to retrieve a primal ray:
int cols;
double *primalRay;
int hasRay;
...
XPRSgetintattrib(prob, XPRS_COLS, &cols);
primalRay = malloc(cols*sizeof(double));
XPRSgetprimalray(prob, primalRay, &hasRay);
if(!hasRay) printf("Could not retrieve a primal ray\n");
Further information
1. It is possible to retrieve a primal ray only when, after solving an LP problem, the final status (
LPSTATUS) is XPRS_LP_UNBOUNDED.
2. Primal rays are not post-solved. If the problem is in a presolved state, the primal ray that is returned will be for the presolved problem. If the problem was solved with presolve on and has been restored to the original state (the default behavior), this function will not be able to return a ray. To ensure that a primal ray can be obtained, it is recommended to solve a problem with presolve turned off (
PRESOLVE = 0).
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