Speedcrunch

SpeedCrunch is a fast, high-precision scientific calculator. It features a syntax-highlighted scrollable display and is designed to be fully used via keyboard.

It includes many built-in maths functions and supports advanced features like user-defined functions, complex numbers, and unit conversions. This is combined with a simple yet powerful user interface featuring on-the-fly results preview, syntax highlighting, and autocompletion.

SpeedCrunch is available for several platforms in a number of languages.