I am looking for an app that will allow me to define some arbitrary formula, enter inputs into it and get some output displayed.

Basically the type of simple formula one can usually uses a spreadsheet to accomplish but with a nice mobile UI.

Is there such an app?

2 Answers 2


An iOS app I like a lot that can do this is Lisping (iTunes and author site page). You can define an "arbitrary formula" as Scheme code, e.g. a function, and then call that code with your inputs and have its output displayed. It's got a nice touch-focused UX for editing code expressions.

The major advantage is that you can use a very elegant and expressive LISP dialect to define your formulae. The major disadvantage is that you must use a LISP dialect and you may dislike doing so. You also may be put off by the idea of programming – but you shouldn't!


Depending on how 'arbitrary' your "arbitrary formula" actually is, you may be just fine with Tydlig (iTunes and author site). It's a really nice touch-focused "calculator reimagined". I'd imagine that you would enter a formula as an expression with specific ('example') values; then you can adjust particular values and Tydlig will show you the new evaluated result of the expression.

  • That actually looks very nice!
    – Ayrx
    Dec 26, 2014 at 7:20
  • Ok, so looking at this further it seems like Tydlig is almost exactly what I want! Just to confirm one thing before I go ahead and get it though, is there support for saving an equation for later use?
    – Ayrx
    Dec 26, 2014 at 10:50
  • @TerryChia you can't save an equation (expression) directly, but everything is saved automatically. What you might want that is not currently available is what the author's refer to as 'multiple canvases' (the canvas is just the visible expressions in the app). See How do I save? on the support page of the app's site. Dec 26, 2014 at 19:56

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