PCalc - PCalc is the powerful choice for scientists, engineers, students, programmers, or indeed anybody...

MATLAB - A high-level language and interactive environment for numerical computation, visualization, and programming

Calculator++ - Calculator++ is an advanced, modern and easy to use scientific calculator.

Wolfram Mathematica - Mathematica has characterized the cutting edge in specialized processing—and gave the chief calculation environment to a large number of pioneers, instructors, understudies, and others around the globe.

Qalculate! - Qalculate! is a multiplatform multi-purpose desktop calculator.

Maxima - Maxima is a fairly complete computer algebra system written in Lisp with an emphasis on symbolic computation.