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# XPRSgetduals

Purpose
Returns the dual values from the incumbent solution during or after optimization of a continuous problem with XPRSoptimize, XPRSlpoptimize or XPRSnlpoptimize.
Topic areas
Solution, LP
Synopsis
`int XPRS_CC XPRSgetduals(XPRSprob prob, int *status, double duals[], int first, int last);`
Arguments

prob | The current problem.
status | Information about the dual solution returned.
duals | Double array of length last-first+1 where the values of the dual variables will be returned. May be NULL if not required.
first | First row in the dual solution.
last | Last row in the dual solution.

Further information
1. The function always returns data in the input space, even if the problem is currently in presolved state. Row indices should be in the range 0 to INPUTROWS- 1.
2. The status will be set to XPRS_SOLAVAILABLE_NOTFOUND ( 0), XPRS_SOLAVAILABLE_OPTIMAL ( 1), or XPRS_SOLAVAILABLE_FEASIBLE ( 2).
3. Dual values are available when the problem is solved with SLP, Knitro or any LP or convex QP algorithm: the status returned will be the same as for XPRSgetsolution. Dual values are not available during or after MIP or global solves: status will be XPRS_SOLAVAILABLE_NOTFOUND.
Related topics
XPRSoptimize, XPRSgetsolution, XPRSgetslacks, XPRSgetredcosts.
Parent Topic Console and Library Functions

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