Qalculate! is a multi-purpose desktop calculator for GNU/Linux (now ported to Mac via MacPorts). It is small and simple to use but with much power and versatility underneath. Features include customizable functions, units, arbitrary precision, plotting, and a user-friendly interface (KDE3 or GTK+).
Qalculate! is has now moved to GitHub (https://github.com/Qalculate).
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