What free mathematics software do you use regularly or recommend for uniqueness ? I use http://www.cs.ubc.ca/nest/imager/contributions/scharein/KnotPlot.html [Broken] for quick graph checks or trivial numeric evaluation/integration. That it allows easy mouse-controlled rotation of 3-d surfaces is a welcome bonus. What do you recommend ? Edit: Whoops. Moderators feel free to move this to software.