I am just using MathCad as an example, as I don't know others. In college I did use something that did good 3D plots, and solved differential equations and performed integration. I was wondering if there were free or low-cost alternatives to these expensive programs. I just need something that can give me a solution to check my work against. I tend to have a problem of knowing when to stop deriving. I'll work on a problem, and wonder if I really have the solution. Since I don't have $100's to purchase something that probably does way more than I need, I'm wondering what other software will be suitable. Thanks.