Source : Free On-Line Dictionary of Computing

Calc
     
         An extensible, advanced desk calculator
        and mathematical tool written in {Emacs Lisp} by Dave
        Gillespie .  Calc runs as part of {GNU
        Emacs}.  You can use Calc as only a simple four-function
        calculator, but it also provides additional features including
        choice of algebraic or {RPN} ({stack}-based) entry,
        logarithms, trigonometric and financial functions, {arbitrary
        precision}, complex numbers, vectors, matrices, dates, times,
        infinities, sets, algebraic simplification, differentiation,
        and integration.
     
        Latest version: 2.02, as of 1994-11-08.
     
        FTP calc-2.02.tar.z from your nearest {GNU archive site}.
     
        (2000-10-20)