Initializing help system before first use

XPRBgetvarrng

Purpose
Get ranging information for a variable.
Synopsis
double XPRBgetvarrng(XPRBvar var, int rngtype);
Arguments
var 
BCL reference to a variable.
rngtype 
The type of ranging information sought. This is one of:
XPRB_UUP 
the change in objective value per unit increase in the variable activity, assuming the the current basis remains optimal;
XPRB_UDN 
the change in objective value per unit decrease in the variable activity, assuming the the current basis remains optimal;
XPRB_UCOST 
the largest value which this variable's objective coefficient can take while the current basis remains optimal;
XPRB_LCOST 
the smallest value which this variable's objective coefficient can take while the current basis remains optimal;
XPRB_UPACT 
for a variable which is at one of its bounds, the largest value which that bound can take while the current basis remains optimal;
XPRB_LOACT 
for a variable which is at one of its bounds, the smallest value which that bound can take while the current basis remains optimal.
Return value
Ranging information of the required type.
Example
This example retrieves the upper objective coefficient range for a variable. 
XPRBprob expl2;
XPRBvar x1;
double ucval;
expl2 = XPRBnewprob("example2");
x1 = XPRBnewvar(expl2, XPRB_UI, "abc3", 1, 100);
 ...
XPRBlpoptimize("expl2, "");
ucval = XPRBgetvarrng(x1, XPRB_UCOST);
Further information
1. This method can only be used after solving an LP problem. Ranging information for MIP problems can be obtained by fixing all discrete variables to their solution values (using XPRSfixmipentities) and re-solving the resulting LP problem.
2. For non-basic variables, the unit costs are always the values of the reduced costs.
Related topics
XPRBnewvar, XPRBgetctrrng.

Parent Topic BCL C library functions

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