GRPN is a graphical reverse polish notation (RPN) calculator.
GRPN is written in C and uses the GIMP Toolkit
(GTK) on top of X11.
GRPN was developed under Linux but has also been tested under SunOS
and Solaris. It should work with almost any UNIX, though.
GRPN works with real numbers and complex numbers. Numbers
can be displayed in 4 different radix modes, and complex numbers
can be displayed in either Cartesian or polar form.
GRPN uses a stack and reverse polish notation to evaluate
expressions. The stack in GRPN is infinite and limited only
by available memory.