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 
10.9.7: Manipulation of Columns etc10.9.7.1: ColumnsIndividual data in the `x ', `y ', `z ', `u ', `v '
and `weight ' columns can be accessed with the `@ ' operator.
The first point has index 0. Examples:
The mean value is available from the `
The minimal and maximal values are given by
`
The area under the curve y=y(x) is found by `
10.9.7.2: GridGrid data can be accessed with e.g. `{rpn grid min } ',
`{rpn grid max } ', and `{rpn grid mean } '.
The value of the grid at a given `
