I use SciMOD, Scientific Modeling.
The software is friendly, and has basic methods to solve linear systems and it has some other numerical methods.
For non linear equations I have to check it out.
Also it includes some FEM analysis to solve PDE's , Linear elastics solid problems, heat transfer and fluids, it could be interesting for other purposes.
Some videos can be seen at:
http://www.youtube.com/watch?v=zecfY_8YPu8
SciMOD is available at :
https://itunes.apple.com/us/app/analysis-center/id418595099?ls=1&mt=12
I hope it be useful.
