- Desmos and GeoGebra are two very powerful online graphing tools. Having gone through a graduate degree in math without benefit of a graphing calculator, I am amazed and delighted by both of these. They offer free accounts that let you save your creations and share them with others. Both are used extensively by teachers who share their materials online, so you can find interactive exercises of all sorts. Both have tutorials to help you learn how to use them. I've used GeoGebra primarily for playing around with geometry and for 3D graphing, and Desmos more for fiddling with functions. Desmos may be easier to get started with, at least for algebra and graphing functions, but GeoGebra may be more versatile, and it's cool to use for exploring geometry without having to know formulas for the shapes. Here's a comparison by a faculty member at Western Illinois University.
- Runiter has a nice graphing calculator that can do 3D graphs. You can do a lot with the free version, or pay more for one of the more powerful editions. It's available for PC, Mac, and Linux. I've not used it in some time, so I can't say how it compares to Desmos and GeoGebra. If you've compared them, I'd like to know what you think.
"Pure mathematics is, in its way, the poetry of logical ideas." ~ Albert Einstein