2 to the power of 10 or 32 or so – he couldn't do this on a normal calculator, so he wanted to do this. He chose :Emacs Lisp, because he decided this is just an editor extension language, so he would truly hit a wall very soon, and then this project will be over. It never did, apparently.
On the one hand, he implemented this amazing functionality. It's like a poor man's Mathematica. It's of course not as good as Mathematica for complex stuff, but it does 3-D matrix operations, it does some analytic operations, integration, differentiation… All implemented there. And it was written in a time when Emacs didn't even have floating point numbers.
Sacha: Wow.
Carsten: It only had integers. He implemented arbitrary precision integers with lists of numbers and he implemented arbitrary floating points calculation with this thing. Today, I think Calc has not been re-written to make use of the internal floating points. All the floating point operations are actually hand- implemented. It's crazy. There's all this complex stuff in there. But on the other hand, he keeps the simple calculator interface. If you use Mathematica, for example, then you have to type all these commands. That's just a lot of typing. The commands you're putting in are complex. While with the Calc calculator in Emacs, it's still you press a key and you get an action, just like you have it on a calculator.
You press the logarithmic key, and logarithm will be calculated. In Calc, it's usually two keys. Usually, it's sort of a category key like arithmetic or matrix or so. Then the second key for the command. It's extremely fast.
It has the best way to work with units of numbers. I'm an astronomer so we deal with big numbers and having the right units ready… when I sit here with my students, very often they come with something with an idea or so, and then I just turn around to my Emacs and make a little estimate using the unit calculation facilities. It's really the fastest and best way to do this. I totally love this.
I have an iPad. The one reason why I hate is that I cannot have Emacs on it just for the calculator. This is how good this program is. It's amazing. I always have the feeling it's not known well enough. This is why I use this chance to make a big advertisement for it, because it's an amazing program. It's really mind-blowing.
