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DSS Supplement

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Vensim DSS is a powerful environment for developing high quality simulation models.  DSS supports all of the capabilities provided by Vensim.  In addition, Vensim DSS has a number of capabilities that go beyond simple model development.  Vensim DSS allows you to extend the Vensim modeling language with your own functions, to build user interfaces for models, and to exercise control over Vensim from other applications or through batch processing.  

This section describes advanced capabilities that require the Vensim DSS license.  Many of these features require software development skills.


Double Precision DSS performs all calculations using double precision floating point.  This provides increased calculation accuracy which may be important for some applications.


Command Scripts allow the definition of batched processes that may then be executed from within Vensim.


External Functions are functions you create that can be called from within a model during a simulation.  External functions are not available on the Macintosh.  Additional documentation is contained in the sample files that ship with Vensim.


Dynamic Data Interchange (DDE) is a mechanism that allows different applications to communicate with each other.   Vensim DSS can serve both as a DDE server and a DDE client. This section describes how to use Vensim as a DDE server and how to call another application during simulation to get data.  Retrieving data using DDE requires the use of external functions.


NOTE:  DDE has been deprecated in favor of newer communications techniques.  Vensim continues to provide support for existing applications.


Compiled Simulations can reduce simulation time (often to as little as one third of what it otherwise would be).


Vensim DLL


The Vensim DLL facilitates the development of custom applications.  This allows you to use Vensim as part of an application written in another language such as Visual Basic. Vensim DLL Overview describes the capabilities of the Vensim DLL.  It also provides an example of an application and describes briefly the other examples that come with Vensim.


DLL Function Details  documents the Application Programming Interface (API) used by Vensim DLL.   There are a number of commands available, although much of the control of Vensim is done through the same commands that Venapps use.


Distributing Your Work describes the different options that allow you to provide your Vensim modeling work to others.