If you want a lighter-weight package featuring a plaintext REPL, a large library of functions, function definition, arbitrary precision, and more (minus solver capability), give Speedcrunch a try:<p><a href="https://heldercorreia.bitbucket.io/speedcrunch/" rel="nofollow noreferrer">https://heldercorreia.bitbucket.io/speedcrunch/</a>
It's a really great calculator for all sorts of stuff.<p>I use many of the following almost daily:<p>- currency conversion: `x USD to EUR` or `BTC to USD`<p>- time calculations: `now - 27 hours`<p>- unix epoch conversion: `timestamp(now - 3 days)`, also `stamptodate()`<p>- unit conversion: `34 oC to oF`<p>and more.<p>Works really nicely with <a href="https://github.com/svenstaro/rofi-calc">https://github.com/svenstaro/rofi-calc</a>
I have it bound to `$mod+c` and launched as a floating window in i3. It integrates very well into my workflow as I can just quickly launch, perform a one-off calc, and close it whether I'm in a terminal or elsewhere. Since it saves history, I can always relaunch it and continue where I left off as well.
The "ultimate" calculator wouldn't use the same irrelevant-in-PC physical number buttons paradigm, taking up more than half of useful UI space
I wanted to chime in as a calculator dev dude. Qalculate is really nice if you want the kitchen sink, which I do on the desktop. I also, depending on the task use speedcruch which others have mentioned.<p>Using <a href="https://github.com/ArashPartow/exprtk">https://github.com/ArashPartow/exprtk</a> I have one calculator with a repl at 512kb, including a QML wrapper. I have a combined rpn calculator using sympy (based on the work of others) with exprtk as a 'programmer's calculator' on the side (<a href="https://github.com/poetaster/fibonacci">https://github.com/poetaster/fibonacci</a>). And several QML apps for symbolic CAS using sympy.<p>I have way too many calculators. They are so much fun to build. Now I ask myself, port the Qalculate methods to macros for exprtk or check out using libqalculate? I'm not sure. exprtk is so light? And adding macros discrete.
As an engineer, I usually can just pop my expression into Siri/Spotlight or Cortana with a hotkey and get the result just fine. What kinds of calculations are people needing more for?
I love qalculate. Now Slackware (my distro) ships libqalculate, and then it's trivial to build a frontend.<p>I loved Qalculate back when it was a KDE3 application. In KDE4 times the UI switched to GTK+, but recently the dev added a newer Qt frontend which is really nice save for the fact that it doesn't have an app menu other than a hamburger menu not really accessible via keyboard; you must use the mouse for it.<p>I'd love to see a KDE Plasma frontend again with the more traditional layout. The app is great and powerful.
It is a very versatile piece of software indeed. The minimal mode window is a great pop-up calculator that can do a lot, including conversions and working with physical units.<p>Highly recommend!
RealCalc free version from Quartic on Android is not bad. Not comparing it to Qalculate.<p>And it has a really cool
physical-world electronic calculator look, hence the name.
I forgot to mention in my last comment that <a href="https://github.com/vetux/qcalculator">https://github.com/vetux/qcalculator</a> is also a nice qt based, exprtk using calculator with a python interface and higher floating point precision than plain exprtk.
Qalculate is great. I also use insect on the terminal for quick calculations or conversions<p><a href="https://insect.sh/" rel="nofollow noreferrer">https://insect.sh/</a>
Obligatory mention for bc, a command line arbitrary precision calculator and language.<p><a href="https://en.wikipedia.org/wiki/Bc_(programming_language)" rel="nofollow noreferrer">https://en.wikipedia.org/wiki/Bc_(programming_language)</a>