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XPRBgetrcost

XPRBgetrcost


Purpose
Get reduced cost value for a variable.
Synopsis
double XPRBgetrcost(XPRBvar var);
Argument
var 
Reference to a variable.
Return value
Reduced cost value for the variable, 0 in case of an error.
Example
XPRBprob expl2;
XPRBvar x1;
double rcval;
   ...
expl2 = XPRBnewprob("example2");
x1 = XPRBnewvar(expl2, XPRB_UI, "abc3", 1, 100);
XPRBlpoptimize(expl2, "");
rcval = XPRBgetrcost(x1);
This retrieves the reduced cost value for the variable x1 in the solution to the LP problem.
Further information
This function returns the reduced cost value for a variable. The user may wish to test first whether this variable is part of the problem, for instance by checking that the column number is non-negative.
Reduced cost information is available only after LP solving. To obtain reduced cost values for a MIP solution (that is, if function XPRBgetmipstat returns values XPRB_MIP_SOLUTION or XPRB_MIP_OPTIMAL), you need to fix the discrete variables to their solution values with a call to XPRSfixglobals, followed by a call to XPRBlpoptimize before calling XPRBgetrcost. Otherwise, if this function is called when a MIP solution is available it returns 0.
If no solution information is available this function outputs a warning and returns 0.
If this function is used during the execution of an optimization process (for instance in Optimizer library callback functions) it needs to be preceded by a call to XPRBsync with the flag XPRB_XPRS_SOL. In this case it returns the reduced cost value in the last LP that has been solved.
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