[SCIP] accessing reduced costs of variables of an LP in optimality

[Ahmad Moradi]

Dear SCIP community,

I am implementing a heuristic algorithm who seeks to find a good (primal)
solution of a given MILP. The algorithm actually starts by looking at
reduced-cost value of variables after solving LP relaxation of the MILP.

I simply coded the LP and solved it. Then I used the method
SCIPgetVarRedcost() to see reduced-cost value of my original LP variables.
However, I noticed that some of the values are negative, contradicting to
optimality as the LP has minimization objective sense. Then I found that
scip is not in the solving stage (SCIP_STAGE_SOLVING) as required by
SCIPgetVarRedcost()... is that the why some reduced-costs get negative? if
so, how can I access correct reduced cost values (according to optimal
basis).

Bests,
Ahmad
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