GNU Octave: a free, open source MATLAB-like language for numerical computing

I tend to use Python with the Numpy, SciPy, and Matplotlib stack whenever I have to do scientific computing. For statistical computing I use R whenever this Python stack does not provide the necessary features. However, I want to draw readers’ attention to another tool for free, open-source numerical computing: GNU Octave (hereafter called “Octave”), […]

proportional-integral (PI) controller in Vensim

In my last post, I discussed an attempt at designing a PID controller using the Kepler Scientific Workflow system. Here I report on a similar (yet successful) development of a proportional-integral (PI) controller in Vensim PLE. Vensim is a software package for describing and simulating dynamic models, particularly those involving feedback. I’ve often described it […]

attempted PID controller with Kepler

I wanted to check out the Kepler scientific workflow system (, and decided to build a PID controller model with it. Here I report on my results. The following schematic, taken from the Wikipedia entry, shows the basic configuration of a PID controller. PID stands for “proportional integral derivative”, reflecting the fact that the […]