Q+ Expressions.

Q+ Version 1.0, which allows expressions to be included in models, is now available to Q+ users on a trial basis. Q+ (formerly PAW) is an interactive visual simulation modeling tool which has been widely used for the analysis of computer, communications and manufacturing systems. The previously provided Monte Carlo simulation capabilities and interfaces to various analytic tools are powerful and allow many complex situations to be easily represented. However, there are cases where it would be more natural to express modes of operation with program fragments, e.g., variables or procedures. This need is met in Q+ Version 1.0 with a new expression capability. The extension to the Q+ paradigm is straightforward; many of the key places where the user previously entered a parameter or distribution are now potential positions for inserting a user-defined expression. Users can also define their own statistics. The expression language adopted by Q+ is called Exp. Exp is fully interpretive, has a C-like syntax, supports lists, and maintains dynamic typing. The user now also has access to the CPI (formerly HPE) library at run time and any other C language function. The combined effect of this enhancement to Q+ is a new mixed paradigm where the user may freely combine visual and textual modeling.