Calca: the notepad calculator

For years, I’ve been searching for a good free-form symbolic calculator program that works across multiple desktop operating systems. I think I’ve finally found one worth mentioning. My goals:

Be able to enter expressions similar to what I could do on a TI-85, back in the day, for example: 2^2+(2*10)
Be able to easily edit and copy previously-entered expressions.
Input/output hex. I work in hex a lot. This includes expressions (0x48+0x16) as well as base conversion (0xC3 as decimal or 0b110101 as decimal) and bitwise math (0xFC AND 0x7F).
Lightweight. Quick to load, quick to calculate. Get in, get out. Or leave it running in the background without eating a ton of resources. I don’t need or want Mathematica or Maxima.
It needs to minimally run on Windows and Mac. Ideally a Linux version would be available, too. I write code on Linux (work) and Mac (home), but my office Windows box ends up being my documentation reference, scratchpad, calculator, and everything else non-coding because I typically run my Linux IDE full-screen (bridged with Synergy, naturally).

I’d previously gotten hooked on Soulver. It’s great on the Mac, but there are not Windows or Linux ports. There is an iOS port, but I can’t stand the data entry. SpeedCrunch is available for all platforms, but like many Open Source programs, the operation and user interface is clunky.

A few months back, I found Calca, “the text editor that loves math,” for Windows and Mac. It literally is a text editor. The trick is that it looks for “=” and interprets these as definition statements and it looks for “=>”, and treats these lines as problems to solve. Everything from “=>” to the end of the line is rewritten to become a read-only answer. For example:

I don’t come close to using all the features in Calca: functions, unit/currency conversion, matrix math, derivatives, and so on. My needs are small, but with the pieces I do use, it performs extremely well.

A few things I don’t like about Calca:

There are no bitwise shifts or inversions. I sometimes run into cases where a 32-bit integer is composed of several unaligned bit fields. For instance, bits 5..7 might be one field. It would be great to say: 0x1234 >> 5 & 0b111
I frequently get confused with base conversion syntax. Is it “as dec” or “in dec”? I frequently pick the wrong one.
Having to type “=>” at the end of each line is typographically awkward. I appreciate Soulver having a second column that auto-updates as you type.
It would be nice to have a “previous answer” symbol. The TI calculators automatically insert an “Ans” variable (a placeholder for the previous line’s answer) if you start a new line with an operator instead of an operand.

For me, it was worth buying both a Windows and Mac license. I use it all the time.

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