Calc is an interactive calculator which provides for easy large
numeric calculations, but which also can be easily programmed for
difficult or long calculations.  It can accept a command line
argument, in which case it executes that single command and exits.
Otherwise, it enters interactive mode.  There are a great number
of pre-defined functions.  The calculator can calculate transcendental
functions, and accept and display numbers in real or exponential format.
The calculator also knows about complex numbers.
