Chapters: 1: Introduction 2: Simple example 3: Invocation 4: Finer Control 5: XY Plots 6: Contour Plots 7: Image Plots 8: Examples 9: Gri Commands 10: Programming 11: Environment 12: Emacs Mode 13: History 14: Installation 15: Gri Bugs 16: Test Suite 17: Gri in Press 18: Acknowledgments 19: License Indices: Concepts Commands Variables 
10.9: Rpn (reversepolish notation) CalculatorGri can do simple mathematics on numbers. The syntax is reversepolish notation (`rpn '), which is used in some calculators. Most users
can learn rpn in a few minutes, so don't worry if you don't know RPN
yet.
Syntax: rpn expressions can be used anywhere Gri expects a number.
RPN expressions start with a opening curly brace (`
If an rpn expression contains a variable whose value is ``missing'', then the value of the result of the expression will also be missing (unless the value of the missing variable is thrown away with a ``pop'' operator). However, if a missing value just happens to occur as the result of an intermediate calculation, then the result is not considered to be missing. RPN operations can be divided roughly into the following groups.
