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The LP Procedure |
When the LP procedure pauses, you can enter any of the interactive statements RESET, PIVOT, IPIVOT, PRINT, SHOW, QUIT, and RUN.
Break points are set using the FEASIBLEPAUSE, PAUSE, IFEASIBLEPAUSE=, IPAUSE=, PROXIMITYPAUSE=, READPAUSE, and ENDPAUSE options. The LP procedure displays a message on the SAS log when it gives you control because of encountering one of these break points.
During phase 1, 2, or 3, the CTRL-BREAK key pauses the LP procedure and releases the control at the beginning of next iteration.
The error conditions, which usually cause the LP procedure to pause, include time limit exceeded, phase 1 iterations exceeded, phase 2 iterations exceeded, phase 3 iterations exceeded, and integer iterations exceeded. You can use the RESET statement to reset the option that caused the error condition.
The PIVOT and IPIVOT statements result in control being returned to you after a single simplex algorithm pivot and an integer pivot. The PRINT and SHOW statements display current solution information and return control to you. On the other hand, the QUIT statement requests that you leave the LP procedure immediately. If you want to quit but save output data sets, then type QUIT/SAVE. The RUN statement requests the LP procedure to continue its execution immediately.
Details about the current status of the solution are obtained using the PRINT statement. The various display options enable you to examine parts of the variable and constraint summaries, display the current tableau, perform sensitivity analysis on the current solution, and perform range analysis.
When you specify /SENSITIVITY in a PRINT ROW (rownames) statement, the LP procedure defines a new change column to use in sensitivity analysis and parametric programming. This new change column has a +1 entry for each right-hand-side coefficient listed in the PRINT statement. This enables you to define new change columns interactively.
In addition, you can interactively change the RHSPHI= and PRICEPHI= options using the RESET statement. This enables you to perform parametric programming interactively.
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