Hungs on close on Snow Leopard.

@guns : This is much faster than Grapher. The developer has worked hard to make it very fast. Longhad also lets you start typing instantly, and calculates on the fly, which is cool.

I like Grapher, but using it for calculating like this is overkill.

I like this app because I can easily define functions it doesn't know (like lg(x) for "log base 2 of x").

Though I haven't tried this application, as a fan of the OS X app Grapher, I would like to mention that Grapher does do calculations in longhand as well (just don't graph a function; leave out any variables). Of course, this program looks pretty great too.