Purpose
Get
ranging information for a variable.
Synopsis
double XPRBgetvarrng(XPRBvar var, int rngtype);
Arguments
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var
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BCL reference to a variable.
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rngtype
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The type of ranging information sought. This is one of:
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XPRB_UUP
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the change in objective value per unit increase in the variable activity, assuming the the current basis remains optimal;
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XPRB_UDN
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the change in objective value per unit decrease in the variable activity, assuming the the current basis remains optimal;
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XPRB_UCOST
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the largest value which this variable's objective coefficient can take while the current basis remains optimal;
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XPRB_LCOST
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the smallest value which this variable's objective coefficient can take while the current basis remains optimal;
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XPRB_UPACT
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for a variable which is at one of its bounds, the largest value which that bound can take while the current basis remains optimal;
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XPRB_LOACT
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for a variable which is at one of its bounds, the smallest value which that bound can take while the current basis remains optimal.
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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
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