FEATURED APP

# Solve Equations as You Type

Part spreadsheet, part writing app, Calca is A1.

Calca

At first glance, Calca looks like a simple text editor, and in many ways it is. You can use it to style text, add headings and links, and create a table of contents. But this one-of-a-kind app is also what you might call a mathematical word processor: a tool for creating documents that center around—and solve—calculations.

The key to Calca is a sequence of two characters: =>. Type it and the app will figure out all manner of calculations, from the simple “6 * 8 – 4 =>” (which yields 44) to the complex. For example, the app is smart enough to understand variables and equations. Enter:

42x – 12y = 294
y=7
x=>

And Calca tells you that x=9.

Feel free to make your annotations as verbose as you like; Calca can handle it. Use the “plot” feature (right) to graph possible outcomes.

Calca also has a simple programming language for creating what it calls definitions—easy-to-read names you can assign to numbers and formulas. For example, wondering how much your vacation will cost? Type in a few lines like:

vacation cost = hotel nightly rate * days of vacation + airfare
hotel nightly rate = \$80
days of vacation = 7
airfare = \$900
vacation cost =>

And Calca tells you the answer is \$1,460.

You can build much more complex sets of calculations and relationships, plugging in various values to see how they affect outcomes. And because you’re free add as much text as you want, Calca offers more flexibility than a rigid spreadsheet.

Calca tackles complex equations with aplomb.

The app has a deep well of mathematical features, including matrices and a plot feature that lets you see a range of possible outcomes at a glance, and it recognizes units of measures and currencies—and handles conversions among them. There’s a lot to explore, so be sure to check out the detailed documentation—conveniently written in Calca documents. It includes live formulas you can experiment with, making neat use of the app itself to help you learn its many capabilities.