Gri: Overview of commands

Gri Commands 1: Introduction 2: Simple example 3: Fancy example 4: Running Gri 5: Programming Gri 6: General Issues 7: X-Y Plots 8: Contour Plots 9: Image Plots 10: Examples 11: Handling Data 12: Gri Commands 13: Gri Extras 14: Evolution of Gri 15: Installing Gri 16: Gri Bugs 17: System Tools 18: Acknowledgments 19: License 20: Newsgroup 21: Concept Index | ## 12.1: Overview of Gri Commands The first word of a command hints at the meaning, but apart from that, here is a rough guide: File manipulation Commands are ``open`', ``close`', ``skip`', ``read`', and ``rewind`'. Control parameters Various ``set`' commands control values of parameters, like size of plot, linewidth, font, etc. Drawing things Various ``draw`' commands let you draw data, axes, etc. Interaction with user The ``query`' command gets instructions from the user. The ``show`' command displays messages to user. Control program flow The ``if`' statement controls optional execution of commands see If Statements. The ``while`' statement allows loops. Directory control The ``pwd`', ``cd`' and ``ls`' commands do the usual unix things. Interaction with operating system The ``system`' command passes instructions to the operating system; the output may be saved into a synonym by using ``\syn = system ...`'. The ``get env`' command determines the value of any unix environment variables the system has defined. For more discussion see Operating System. Statistics Some very limited capabilities exist; for example, ``regress`' does linear regression. Mathematics Simple mathematical manipulation of column, grid, and image data is provided. Also, wherever Gri expects a number, it will accept a reverse-polish expression; for example, ``set x size 10`' could also be written ``set x size {rpn 20 2 /}`'. For details see Mathematics. The data types in Gri are columns, grids, images, scalar variables and ``synonyms'' that is, strings see Synonyms, see Variables.