Gnomon is an interactive, programmable calculator with a standard library of mathematical, statistical and plotting functions.

The name Gnomon comes from an ancient Greek word signifying "one that knows", an interpreter, discerner. (In English the word is used to describe the shadow casting indicator of a sundial.)

Calculations can be entered directly into the interactive command table, and a history is maintained. A custom keyboard accessory minimises the need to switch keyboards while entering mathematical symbols. Freeform text entry via worksheets is also supported, and maintained between invocations.

Large output and graphics are shown in abbreviated form but can easily be recalled. Plots can be scaled, saved, and 3D plots can be rotated.

Command entry may be anything from simple expressions to complicated user functions, loops, conditions. Data in the form of integers (arbitrary precision), fractions, decimals, complex numbers, arrays, strings, stacks and dicionaries are natively supported. Extensive help is included with the app, and the freeform worksheets are pre-populated with illustrative examples.

Scroll the main window horizontally to switch between the various modes of operation - interactive, freeform, function reference and help.