Sometime in 2000 I was sort of challenged to make a cool graphing calculator application. It’s a stupid story, but this program is the end result. I know it’s horribly under-featured (fixed axis, no scaling, poor painting refresh, no options, etc) but i had never intended this for public use.
Probably the hardest part was making the equation parser/interpreter. In retrospect, I did a horribly messy and inefficient job with it, but it works. The graphics were surprisingly easy.
For now, I think it supports abs, sin, cos, tan, asin, acos, atan, log, ln, +, -, *, /, ^ and maybe some others I’m forgetting.