I have an extcalc program on my computer. I can't seem to figure out how to get it to plug in "y" variables. (eg. x^2 + y^2) Your widget did this without any problem. (Looked great.) I am just getting underway with trying to understand -- in an elementary way -- certain areas of math based physics. I use a Linux platform. Ubuntu. Do I need a good tutorial on extcalc or would some other program that I could download meet my needs better?