Vensim 6.3 Released

Get It

Vensim 6.3 is available for download or purchase in the Vensim Store .

Upgrades are easy – just visit the download page and enter your license key information.

  • If your maintenance is current, you can download immediately.
  • If you don’t have a current license, you can extend your maintenance easily – just follow the Upgrade link that will be generated.
  • Can’t find your license? Need other options? No problem – contact sales at for help, volume quotes and other information.

PLE is always free for noncommercial use, and the Model Reader is free for redistribution of any model.

What’s New?

6.3 emphasizes engine improvements that keep Vensim #1 when it comes to industrial strength simulation:

  • Random Numbers & Sampling
    • A new pseudorandom number generator, extensively tested with the Statistical Test Suite from the National Institute of Standards – great for financial, stochastic or statistical models that are heavy consumers of random numbers.
    • Optimization and sensitivity control files may now specify a random seed of 0 to trigger randomization to system cryptographic sources (useful for performing independent runs on multiple computers without editing the control files).
    • Improved sampling for Sensitivity (Monte Carlo) Simulations.
  • Optimization
    • Big improvements to Markov Chain Monte Carlo and Simulated Annealing performance
    • A broader distribution of initial test points in random multistart optimization (MWYS), to find optimal solutions faster (up to 100x in one test case).
    • Improved speed in stochastic optimization, with support for the File sensitivity control option.

There are also some usability upgrades, like better number formatting and placement of the workbench variable in the bottom status toolbar.

See the release notes for details.

There’s a quick introduction to Vensim in the Video Library.

Vensim 64

A 64-bit beta version is available for download to Vensim Pro and DSS users who are current with their maintenance. It’s full-featured and supports huge models.

Vensim 6

If you’re not current with Vensim 6, there are some valuable new features, including:

  • Native Mac support (licenses are portable across platforms)
  • GET DIRECT functions that can access spreadsheets and other delimited data files, like the GET XLS functions without the overhead of launching Excel.
  • Significant upgrades to the Help system, including improved indexing and nearly 100 sample models illustrating the use of almost every built-in function
  • A new Equation Editor
  • Improved Toolbars and Cursors
  • The option of observing integer constraints in the ALLOCATE AVAILABLE function – great for managing allocation of discrete items like customers or aircraft.
  • On-the-fly configuration of subscripts (arrays) with the GET DIRECT SUBSCRIPTS or GET ODBC SUBSCRIPTS functions – great for matching model detail to your data.
  • :EXCEPT: statements that let you handle exceptions to subscripted equations more easily.
  • Optimization features
    • Stochastic optimization : optimize over an ensemble of Monte Carlo simulations
    • Discrete constraints on optimization parameters, so you don’t waste time determining whether to build 2.6 or 2.7 factories.
    • Extended payoffs with non-Gaussian errors, logarithms, and mixed calibration/policy variables.
    • Markov chain Monte Carlo & simulated annealing
    • Extended payoff report information with MAPE and Theil statistics

Feedback from our users who’ve upgraded to version 6 has been highly positive. Contact us for details on any of these.