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Hi all, as a hobby I've been developing a scientific calculator with some neat features. Available on: * web (mobile or desktop): https://alexbarry.github.io

by axby 5y ago

Hi all, as a hobby I've been developing a scientific calculator with some neat features. Available on: * web (mobile or desktop): https://alexbarry.github.io/AlexCalc/ https://alexbarry.github.io/AlexCalc/ * Android: https://play.google.com/store/apps/details?id=net.alexbarry.calc_android https://play.google.com/store/apps/details?id=net.alexbarry.... Some neat features: * LaTeX equation display (I hated counting brackets on my old graphing calculators back in college, now I wouldn't have to if I wasn't ~10 years late in making this) * variables (you can store variables with `1 + 2 -> x`, then access them `x^2 - 3`) * unit operations, and unit conversions, e.g. `10 km / 2 minutes to mph`, or more fancily: `sqrt((3 kOhm + j*100 mH * 1000 kHz)/(1 S + j * 1 nF * 1000 kHz))` * complex numbers (specifically focused on making it easy to enter complex numbers in polar form, in degrees, e.g. `5 angle 90`, but press the "degree" button) * can enter input either via button presses or typing, so copying and pasting inputs works well The core calculator parsing, evaluating, and LaTeX generation is in C++, with CMake build files. Using emscripten[0], this compiles to webassembly for the web version, and I can also compile this for Android and use JNI. The library converting my generated LaTeX code to graphics is "MathJax"[1], a really nice browser library that I loved working with both in the web version and in the Android WebView. I'm happy to receive any feedback at all. One big weakness currently are the syntax error messages, I haven't yet implemented a way to point to a particular position where an error occurs. If there is some nice parsing library that I could use instead, I might consider switching to that if it isn't too difficult. Currently the parsing uses a bunch of (fairly simple) regular expressions (e.g. check for number, check for optional unit, check for binary operator, add to stack, collapse stack. This ends up with a tree of nodes, and then this tree can either be evaluated or converted to LaTeX.) I'm also interested in hearing any strategies for a decent cross platform UI. I didn't want to just include the HTML UI in a WebView on Android, since I figured it wouldn't be a great user experience. Originally I thought it would be small enough that I could just write two separate copies... but it turns out that there is a lot more UI code than I expected (automatically insert multiplication symbols on button presses, input history, storing "recently used units" when the button is pressed, etc...) [0]: https://emscripten.org/ https://emscripten.org/ [1]: https://www.mathjax.org/ https://www.mathjax.org/

enriquto 5y ago
Hey, it looks great, I love it! Would it be feasible to support unicode variables? Having to spell the greek letters seems a bit clunky. If I type them directly it gives a parsing error. Notice that in modern LaTeX (say, xetex or luatex) you can do that. No need to type \'e to get é like we did in the nineties.
- axby 5y ago
  Thanks a lot for trying it and the feedback! Assuming C++ standard regex supports unicode, then this should be easy enough. I never thought to try this. I'll see if I can implement it later today or this weekend. Do you think the spelled out "alpha" should map to the same thing as "<unicode alpha character>"? Also, do you mind if I ask how you are entering Greek letters directly? (e.g. are you a Greek speaker, using a Greek keyboard?) I'd like to better understand how people would like to use this. I'm happy to accommodate whatever I can, and I'm relying on people asking for it directly since I don't have any sort of tracking implemented. (The android version doesn't even request any INTERNET permission (or any permission).)
  - enriquto 5y ago
    > Also, do you mind if I ask how you are entering Greek letters directly? I've setup my keyboard (on linux) so that the CAPS-LOCK key acts as a "dead greek" composer. If I press "CAPSLOCK+a" it types "α", and so on. > Do you think the spelled out "alpha" should map to the same thing as "<unicode alpha character>"? My unpopular opinion is that typing "alpha" should compute the product of the five values, equivalent to "a^2lph".
    - axby 5y ago
      > I've setup my keyboard (on linux) so that the CAPS-LOCK key acts as a "dead greek" composer. If I press "CAPSLOCK+a" it types "α", and so on. Cool! Is this because you type a lot of Greek (or math)? > My unpopular opinion is that typing "alpha" should compute the product of the five values, equivalent to "a^2lph". I wouldn't call it an unpopular opinion, that's how my physical graphing calculator worked, though it only had single letter variable names. The programmer in me likes my current way, though the (nearly long gone) engineering student cringes when I have to write things like "i*2*pi*f". If people were mostly universally happy with single letter variable names then I could probably switch to this. If they were space separated then it would be a fairly simple change (except for the way units works, is "1 s" 1 times variable s, or 1 second? This is why I don't support 1 m/s to mean metre per second, it means "1 metre divided by variable s". 1 metre per second is "1 m s^-1"). I tried to compromise by making the UI automatically enter a multiplication symbol when entering tokens that aren't valid. Perhaps if I added an additional input layer when typing then this would be feasible. Maybe something like pressing a special character, then typing "alpha" will convert it to the alpha character, and non greek letter variables could be wrapped in quotes or square brackets or something. The one thing that would be lost is the ability to name a variable "x2". Maybe that's fine since "x_2" would still work. As an update on unicode parsing, I still think it should be easy, but I'm running into issues. I quickly tried https://stackoverflow.com/a/11255698/9596600 https://stackoverflow.com/a/11255698/9596600 but I'm seeing this: terminate called after throwing an instance of 'std::regex_error' what(): Unexpected escape character. I suspect I just need to dig in on how to use these extended regexes (and remove some of my existing regexes). This weekend I might have more time to try it.

by axby 5y ago

enriquto 5y ago

Hey, it looks great, I love it! Would it be feasible to support unicode variables? Having to spell the greek letters seems a bit clunky. If I type them directly it gives a parsing error. Notice that in modern LaTeX (say, xetex or luatex) you can do that. No need to type \'e to get é like we did in the nineties.

axby 5y ago
Thanks a lot for trying it and the feedback! Assuming C++ standard regex supports unicode, then this should be easy enough. I never thought to try this. I'll see if I can implement it later today or this weekend. Do you think the spelled out "alpha" should map to the same thing as "<unicode alpha character>"? Also, do you mind if I ask how you are entering Greek letters directly? (e.g. are you a Greek speaker, using a Greek keyboard?) I'd like to better understand how people would like to use this. I'm happy to accommodate whatever I can, and I'm relying on people asking for it directly since I don't have any sort of tracking implemented. (The android version doesn't even request any INTERNET permission (or any permission).)
- enriquto 5y ago
  > Also, do you mind if I ask how you are entering Greek letters directly? I've setup my keyboard (on linux) so that the CAPS-LOCK key acts as a "dead greek" composer. If I press "CAPSLOCK+a" it types "α", and so on. > Do you think the spelled out "alpha" should map to the same thing as "<unicode alpha character>"? My unpopular opinion is that typing "alpha" should compute the product of the five values, equivalent to "a^2lph".
  - axby 5y ago
    > I've setup my keyboard (on linux) so that the CAPS-LOCK key acts as a "dead greek" composer. If I press "CAPSLOCK+a" it types "α", and so on. Cool! Is this because you type a lot of Greek (or math)? > My unpopular opinion is that typing "alpha" should compute the product of the five values, equivalent to "a^2lph". I wouldn't call it an unpopular opinion, that's how my physical graphing calculator worked, though it only had single letter variable names. The programmer in me likes my current way, though the (nearly long gone) engineering student cringes when I have to write things like "i*2*pi*f". If people were mostly universally happy with single letter variable names then I could probably switch to this. If they were space separated then it would be a fairly simple change (except for the way units works, is "1 s" 1 times variable s, or 1 second? This is why I don't support 1 m/s to mean metre per second, it means "1 metre divided by variable s". 1 metre per second is "1 m s^-1"). I tried to compromise by making the UI automatically enter a multiplication symbol when entering tokens that aren't valid. Perhaps if I added an additional input layer when typing then this would be feasible. Maybe something like pressing a special character, then typing "alpha" will convert it to the alpha character, and non greek letter variables could be wrapped in quotes or square brackets or something. The one thing that would be lost is the ability to name a variable "x2". Maybe that's fine since "x_2" would still work. As an update on unicode parsing, I still think it should be easy, but I'm running into issues. I quickly tried https://stackoverflow.com/a/11255698/9596600 https://stackoverflow.com/a/11255698/9596600 but I'm seeing this: terminate called after throwing an instance of 'std::regex_error' what(): Unexpected escape character. I suspect I just need to dig in on how to use these extended regexes (and remove some of my existing regexes). This weekend I might have more time to try it.