Graph Toy, an interactive graph visualizer using mathematical functions
This reminds me of my favourite Windows application ever: EvalDraw.<p>It's like this, except that beyond drawing single-argument f(x) -> y functions, it also draws f(x, y) -> z heatmaps, f(x, y) -> (R, G, B) colored heatmaps, f(x, y, z) -> (R, G, B) volumetric 3D graphics, and all these have also a f(..., t) -> ... variant for animations. And then you dig in and discover it somehow also has keyboard & mouse input handling, can play sounds (and can be used for live procedural music), simulate a piano keyboard, and probably a bunch of other stuff I'm forgetting. It was my go-to tool for visualizing any kind of math back during the university years.<p>In fact, I just took a look at it again (after not using it for years) and I discovered it has networking capability, IDE features, and - I kid you not - it seems to compile the scripts down to native code, offering a helpful x86 ASM output in the built-in debugger. It can dump executables, has bindings to OpenGL and support for old-school VR (colored stereoscopic, NVidia 3DVision).<p><i>All in an executable that weighs 746 KB.</i><p>It's hands-down one of the most impressive pieces of software I have ever seen.<p><a href="http://advsys.net/ken/download.htm#evaldraw" rel="nofollow">http://advsys.net/ken/download.htm#evaldraw</a><p>EDIT: And if you give it a try, be sure to check some of the ridiculous amount of examples it comes bundled with, which include games, explorable explanations, infinite calendars, optical systems simulations, and a whole host of other stuff.