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One needs to be aware that the GAMS default bound used to limit the maximum value of the integer variables to 100 but as of version 23.1 this can be changed to +inf by altering a parameter.
This is controlled using the GAMS parameter PF4=n.
| • | Pf4=0: A default upper bound of +INF will be passed to the solver. |
| • | Pf4=1: Bounds of 100 will be passed to the solver as with older GAMS versions. In addition messages will be written to the log and listing to report on the number of integer or semi-integer variables which had bound set to 100. |
| • | PF4=2: The new default values of +INF will be used as with PF4=0. When a solution is returned to GAMS and the level value of an integer variable exceeds the old bound value of 100, a message will be written to the log and listing. |
| • | PF4=3: The same as PF4=2 with an additional execution error issued if the solution reports a level value greater than 100 for any integer variable with a default bound of +INF. |
If the GAMS parameter PF4 is not used GAMS defaults to PF4=1 or bounds of 100 and the problem bounds will be the same as in previous releases.
Setting PF4 values to 2 and 3 is a convenient way to test if the application relies on the previous default bounds of 100.
Future releases may use PF4=0 as the default.
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