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Calca iOS - Mathematical text editor for engineers (praeclarum.org)
94 points by AndreasFrom on July 9, 2013 | hide | past | web | favorite | 37 comments

This looks interesting, but I can't see myself using it on an ipad or phone. This is something I'd want to use on a desktop, with a keyboard, while multitasking with other programs.

Edit: I'll keep it in the back of my head, and I might try it later.

Hi I'm the author. Yep Mac is done and just being submitted for review. I just couldn't resist announcing the iOS version.

+1 to this. Would really like to try this out on the desktop.

Looks quite powerful already. With a few more standard probability/ and statistics-related functions I could see this becoming an excellent tool for finance and consulting work.

You should add an "email me when the Mac version is ready" signup form. Because I will forget about this if you don't remind me, but I'm willing to buy as long as the price isn't significantly higher.

If you want to manually email me when it's done my address is in on my profile page.

This looks really cool!

Will the desktop version have the ability to use functions from third party libraries?

We have a bunch of complicated maths in a java library. At the moment I've got a jruby wrapper around it and using the jruby repl, but it would be awesome if I could use this with it.

Oh interesting. No support for that now, but it should be possible to add. Perhaps shelling out and just reading stdout? Binary interfaces would be harder.

Well luckily, "(and soon OS X app)."

Looks like an interesting halfway house between a text editor and a full-blown CAS like Mathematica (since I have a license, that's what I use as a scratchpad for this kind of thing). It also seems to overlap with Soulver, which is my go-to calculator on iOS.

Cleverly, Calca appears to go a bit further than even MMA by back-filling changed definitions, almost like functional reactive programming. This is neat and something I've wanted to see for a long time.

I'll be buying once I get home to my iPad, but I really want to see the Mac OS version!

Hi I'm the author. I took a lot of inspiration from Soulver. I basically wanted a smarter Soulver with more programming constructs and better treatment of undefined variables. Hope you like it and OS X version will be out in a couple weeks.

I do. I've had a chance to play with it on my iphone and I'm impressed: it does a lot more than I expected it to.

I'll definitely be buying your OSX version. Have you settled on a price yet?

I continue to be baffled as to why black-box modules like this aren't more used by programmers. Code is quick to write, but it obscures structure.


Glad to see Soulver [1] has some competition.

[1] http://www.acqualia.com/soulver/

I absolutely love Soulver, but I think it's trying to achieve a subtly different aim. Soulver is a lot more focused, and definitely more a calculator (albeit one re-designed for the modern era) than a text editor.

What I'd really like to see is something like this, but with in-line typesetting. Similar to the Markdown editors where when the line is active and you're editing it you see the raw text, but when you move off to another line you see the typeset mathematics. Because at the moment, it's just so much quicker and easier to think with pen and paper when you can actually write and read correct notation, rather than a monospaced-ASCII-fascimile...

Soulver groks magnitudes of bits and bytes, and carries units or denominations over, making it invaluable for quick scalability planning or bandwidth estimates and sharing the templates with teams via Dropbox. Love this tool.

There is another similar app called MathPad, a Mac app first released twenty years ago:


It would be really neat if you could tap a number and drag it left or or right to adjust it's value. Everything would recalculate and you could have a small dialog box out to the side to adjust the increment level of the 'drag adjustment'. An iPhone screen probably wouldn't have room for the dialog box so you could putting it in settings but for iPad it would fit just fine.

Agreed! I have this exact feature on the todo list. It just didn't make it for v1.

I certainly can't speak for others, but my typical use case is projected to be in meetings. Imagine sitting in a room with a bunch of engineers and managers, and someone says something worth checking the math on.

If you're not the lucky dude at the conference room's computer and just happens to have IPython Notebook/LightTable/Excel/`w/e`, then this will be handy. Be the guy who keeps up with the conversation and can check assumptions.

The fact it allows variable names with spaces is just the sweetest syntactic sugar.

It runs a smidge slow on the iPhone, but since that's the tool I have on hand, I'll gladly take a lightweight equation solver like this. (And if the slide-to-change numbers feature gets added, I'll happily buy it again. Twice.)

Glad you like the spaces in names! It's not hard to implement without too much ambiguity. :) There are a few tricks I need to pull to make things like: `if x then y else z` be interpreted correctly.

Fun fact: The slowness is bottlenecked by how fast I can update the text editor - the calculations themselves usually only take 10% of the update time. It's a big area that can be improved.

Interesting. I really had just assumed the iPhone was under-powered (having no idea what the device is really doing in the background). If it can go faster, that would certainly be icing. But over all, I think I'll largely be using it to sketch an idea here or there, and it is plenty fast for that. The slowdown is only noticeable for the included big reference documents. (Which are great - being able to twiddle with the features inside the definitions is now my favorite way to learn.)

Looks reasonable.

However you'll have to prize my HP 50g calculator out of my cold dead hands before I'll mix mathematics and a touch screen.

A few suggestions, since the author seems to be hanging around in this thread:

It would be good if plurals for variable names were the same as the singular, so that

light speed = 299,792,458 meters/second

Would be compatible with

time to earth=> 499.242173411seconds

Also, it would be nice if "per" was equivalent to /

Also, it would be nice if definitions didn't have to be

Single item on the left = many things on the right. For example, this would be nice:

Miles per gallon = 34 Gas tank = 13 gallons Range = miles per gas tank

So far I'm having a lot of fun and already posted it to Facebook.

I like it. I'm always typing simple calculations into the search bar -- this is a great way to keep track of them.

Is there anything like this for stats? I remember watching my then girlfriend in the throes of her thesis, having to tweak and re-run a Stata script again and again and again.

Also, for seriously complicated work, maybe a desktop all in one touch screen could be useful, so long as it's oriented more horizontally than vertically.

R + RStudio + Knitr is pretty solid, but more than a bit clunky - write Markdown, intersperse R to your heart's content, and you can execute lines as you see fit.

I have very high hopes for an R + LightTable integration.

R + LightTable would be lovely. As almost everyone else, I use a gross combination of the R GUI (Mac), Emacs, and Sweave.

I am not a huge fan of markdown other than as a "with benefits" convention for text documents, but I see a fair amount of superiority over Sweave/LaTeX for short documents and literate programs.

I see that most people use embedded LaTeX for expressions in various markdown implementations. Is this canonical or is this the result of 'improved' implementations such as Pandoc, etc.?

Btw, OP, you got your $2.99 - royalty from me because I want yet another reason to tell people there is no reason for them to have their laptops open in meetings.

I like it, going to have to start using this more and can't wait for the desktop app.

Just a heads up, when creating a new document in ios 7 beta 3 on the ipad there is a crash. Author, what is the best way to send you the crash log?

Just something to look into before ios7 releases.

In the Introduction, under functions:

  f = m*a
  f(20) = 20a
Which is ok, but then farther down:

  f(a) = m*a
  f(20) => 20a
This seems incorrect, since I was expecting m*20. On a separate page, this seems to work fine, though.

Otherwise, quite nice.

Bug in the doc. :-) just ran on the device and got the expected:

    f(a) = m*a
    f(20) => 20m

Here's another take on it, albeit more for financial computations.

Includes a formula preview: http://numbercanvas.com/

I bet he's excited to see what he can do with CoreText and iOS7 for this.

Any windows/web edition in your todo?

interesting, but how much is this different from ipython notebooks?

This app has automatic re-evaluation when a something changes, like a spreadsheet; ipython notebooks do not.

Or Mathematica?

I still use my TI-89.

Can you embellish a bit, perhaps enlighten us as to why you continue to use your TI-89? How do you think it compares to this, decidedly different, option? My apologies if you accidentally posted that comment before finishing your thought, but I'm generally used to seeing more effort being put into posts on HN.

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