Lo

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Variables and equations have a lower bound.  The lower bound for a variable is the smallest value that the variable can take on.  The lower bound for an equation is the right hand side for a greater than or equal to and equality constraint.  It is minus infinity for a less than or equal to constraint.  The attribute is addressed using .Lo as follows

 

Variable lower bound is variablename.lo(setdependency)

Equation lower bound is equationname.lo(setdependency)

 

These are commonly used in calculations pre solution to specify or revise the bound.

Example:

(varmodatt.gms)

Move.lo(source,sink)=0.1;

solve transport using lp minimizing cost;

display sinkdemand.Lo;

Notes:

•The lower bound is also changed when the fx attribute for a variable is set.
•The lower bound defaults to 0 for positive variables or –inf for other unrestricted or negative variables.
•The lower bound defaults to -inf for less than or equal to equations.