# Free software for modeling complex systems **URL:** \ **Category:** Factual Questions\ **Created:** [July 12, 2010, 12:28pm UTC](https://boards.straightdope.com/t/free-software-for-modeling-complex-systems/546378 "2010-07-12T12:28:26Z")\ **Posts on this page:** 5\ **Page:** 1
**Author:** ![Rhythmdvl](https://avatars.discourse-cdn.com/v4/letter/r/85f322/32.png) [@Rhythmdvl](https://boards.straightdope.com/u/Rhythmdvl)\ **Post date:** [July 12, 2010, 12:28pm UTC](https://boards.straightdope.com/t/free-software-for-modeling-complex-systems/546378/1 "2010-07-12T12:28:26Z")
A little over a decade ago, I had a chance to work with some powerful (to an undergrad) software that graphically and intuitively modeled complex systems. The program allowed you to draw various classes of objects (e.g., things that produced outputs, took inputs) and assign mathematical rules for how they behaved. You could draw arrows between objects to define relationships. After you clicked start, it would chug through the calculations, eventually ending up in stasis or some sort of positive/negative feedback loop. To an undergrad studying climate change and other complex systems at the Biosphere 2, it was an incredible learning tool. It was called [Stella](http://www.iseesystems.com/softwares/Education/StellaSoftware.aspx), and it’s still around—but with a price (and feature set) that’s far beyond me. Anyone know of a freeware program that does something similar? Given that I was impressed by 1996 computations, I’m not really looking for much. Thanks, Rhythm ---
**Author:** ![Superfluous\_Parentheses](https://avatars.discourse-cdn.com/v4/letter/s/8edcca/32.png) [@Superfluous\_Parentheses](https://boards.straightdope.com/u/Superfluous_Parentheses)\ **Post date:** [July 12, 2010, 2:25pm UTC](https://boards.straightdope.com/t/free-software-for-modeling-complex-systems/546378/2 "2010-07-12T14:25:21Z")
It sounds vaguely like something that could be done in [Pure Data](http://en.wikipedia.org/wiki/Pure_Data) or [JMax](http://en.wikipedia.org/wiki/Jmax). I’ve also used similar software at university but that was decades ago and I can’t remember the name. ---
**Author:** ![DrCube](https://avatars.discourse-cdn.com/v4/letter/d/a3d4f5/32.png) [@DrCube](https://boards.straightdope.com/u/DrCube)\ **Post date:** [July 12, 2010, 4:21pm UTC](https://boards.straightdope.com/t/free-software-for-modeling-complex-systems/546378/3 "2010-07-12T16:21:07Z")
Sounds a lot like [Simulink](http://en.wikipedia.org/wiki/Simulink). That is far from free, however. The reason I brought it up is that Simulink runs on MATLAB, which has a free GPL cousin called [Octave](http://en.wikipedia.org/wiki/GNU_Octave). So maybe there is a free alternative to Simulink based in Octave? ---
**Author:** ![MightyDave](https://avatars.discourse-cdn.com/v4/letter/m/ea666f/32.png) [@MightyDave](https://boards.straightdope.com/u/MightyDave)\ **Post date:** [July 13, 2010, 1:13am UTC](https://boards.straightdope.com/t/free-software-for-modeling-complex-systems/546378/4 "2010-07-13T01:13:52Z")
Perhaps Vensim PLE is what you are looking for. It is free (but there are also more capable versions that are not free). [http://www.vensim.com/venple.html](http://www.vensim.com/venple.html) ---
**Author:** ![rlofsted](https://avatars.discourse-cdn.com/v4/letter/r/a4c791/32.png) [@rlofsted](https://boards.straightdope.com/u/rlofsted)\ **Post date:** [July 14, 2010, 9:59pm UTC](https://boards.straightdope.com/t/free-software-for-modeling-complex-systems/546378/5 "2010-07-14T21:59:23Z")
I bought Stella, too, because it is/was Apple’s update to Dynamo, a DOS-based dynamic systems modeling program. In graduate school (science of complexity) we used the latter program effectively, but Stella promised to be much more intuitive. Unfortunately, it appears to be useable only by PowerPC/Classic 9 operating system(s), since I cannot open it up with my MacBook Pro with the Intel chip. With any luck, Stella’s software team is currently working on an update. You might “inquire within.”