I just graduated, and one of my last classes in school was computational physics. We would write programs using C++ to simulate all sorts of physical situations, write a bunch of data to a text file, and then import that data into Mathematica, where we would use the data to create graphs, animations, manipulations, etc. I really enjoyed this class, and I wanted to keep messing around with these sorts of problems on my own. The problem is, I'm not very computer savvy outside of Mathematica, and now that I've graduated I don't have access to that. I can still program and generate data, but I was wondering if anyone knows of a free substitute for Mathematica when it comes to producing visualizations from .txt data. It obviously doesn't have to do all the other stuff Mathematica does, I just want to make pretty graphs and animations from my data (something like manipulations would be a nice perk as well, but that seems like it would be harder to find). Any suggestions?