YarrRPN

Design

A lot of work goes into determining the layout and the expected behaviour of a scientific calculator. YarrRPN is the fruit of a relatively long design process in which many versions of the button layout were tested and iteratively improved.

Genesis

It all started on a whiteboard with a stack of Post-it notes. Moving around physical pieces of paper is the best way to try out button layout configurations.

Prototyping

Once the button layout was almost done, the first graphical prototypes were made. Then, the calculator was developed. The visual design, inspired by the Apple Keyboard, was tweaked and improved upon as the project progressed.

Screenshots

Basic mode

When you hold your iPhone or iPod touch vertically, YarrRPN is a basic Reverse Polish Notation (RPN) calculator.

Scientific mode

Turn your device on its side and YarrRPN calculator will turn into a powerful scientific calculator.

Divide by zero?

Try to perform an illegal operation, like a division by zero, and the calculator's display will turn red for a second.

Settings

The settings screen allows you to tweak your calculator.

Note: Screenshots taken from version 1.0, in December 2009.