Vensim

Vensim is a simulation software developed by Ventana Systems. It primarily supports continuous simulation (system dynamics), with some discrete event and agent-based modelling capabilities. It is available commercially and as a free "Personal Learning Edition".

Vensim
Developer(s)	Ventana Systems, Inc.
Initial release	1990 (35 years ago) (1990)
Stable release	Version 9.3.2 / July 2022 (2 years ago) (2022-07)
Written in	C
Operating system	Windows and OS X applications, Linux and iOS libraries
Type	Simulation software
License	Proprietary
Website	vensim.com

Modeling environment

Vensim provides a graphical modeling interface with stock and flow and causal loop diagrams, on top of a text-based system of equations in a declarative programming language. It includes a patented method for interactive tracing of behavior through causal links in model structure (the patent expired in 2012),^[1][2][3] as well as a language extension for automating quality control experiments on models called Reality Check.^[4]

The modeling language supports arrays (subscripts) and permits mapping among dimensions and aggregation. Built-in allocation functions satisfy constraints that are sometimes not met by conventional approaches like logit.^[5] It supports discrete delays, queues and a variety of stochastic processes.

There are multiple paths for cross sectional and time-series data import and export, including text files, spreadsheets and ODBC. Models may be calibrated against data using optimization, Kalman Filtering^[6] or Markov chain Monte Carlo methods. Sensitivity analysis options provide a variety of ways to test and sample models, including Monte Carlo simulation with Latin Hypercube sampling.

Vensim model files can be packaged and published in a customizable read-only format that can be executed by a freely available Model Reader. This allows sharing of interactive models with users who do not own the program and/or who the model author does not wish to have access to the model's code base.^[7]

Applications

Vensim is general-purpose software, used in a wide variety of problem domains. Common or high-profile applications include:

• Transportation and Energy^[8][9]
• Business Strategy^[10]
• Health^[11]
• Security and Terrorism^[12]
• Project Management^[13]
• Marketing Science in Pharmaceuticals and Consumer Products^[14]
• Logistics^[15]
• Environment^[16][17][18]

See also

• Comparison of system dynamics software
• Computer simulation
• List of computer simulation software
• Monte Carlo simulation