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yorick

NAME

yorick - interpreted language for numerical analysis and postprocessing

SYNOPSIS

yorick [ -i file1.i [ -i file2.i [ ... ]]]
yorick -batch file.i

DESCRIPTION

Yorick is an interpreted language like Basic or Lisp, but far faster. It features:

*

A C-like language, but without declarative statements. Operations between arrays produce array results, which is one reason for Yorick's high speed.

*

An X window system interactive graphics package. Concentrates on x-y plots and filling and contouring quadrilateral meshes. Also handles cell arrays. Graphics can be output to binary CGM or PostScript files as well. A separate CGM browser, gist(1), is included.

*

A binary file package which can read or write floating point formats which are foreign to the machine where Yorick is running. Thus, you can share binary files freely on a heterogeneous network.

*

A library of functions written in the Yorick language. These include Bessel, gamma, and related functions, multiple key sorting, spline, rational function, and least squares fitting, and routines to read and write netCDF files.

*

Provisions for embedding compiled subroutines and functions within a Yorick interpreter. A compiled package which solves matrices and performs FFTs is supplied.

You cannot learn to program in Yorick by reading this man page. Instead, start Yorick (with no arguments) and type:
         help
This will tell you the name of the Yorick site directory at your site. The site directory contains a doc/ subdirectory; read the README file there to find out about more documentation. The Yorick user manual is in project GNU's TeXinfo format, which can be either printed or read online as hypertext using the info command in GNU Emacs. Also available are a set of six quick reference sheets (as PostScript), and alphabetized collections of all of Yorick's online help comments (accessible via the help command). Finally, the i/ subdirectory of the Yorick site directory is a library of functions which are written in the Yorick language, which are also helpful as examples of how to write Yorick programs.

To demonstrate Yorick, start Yorick and type the following two lines:
         #include "demo1.i"
         demo1
After the little movie runs on your X window system display, try:
         help, demo1
Follow the SEE ALSO references in this help message by issuing additional help commands. Also, the help command will print the full pathname of the demo1.i file. Read this file to see how the demo1 function works. You can repeat this procedure with demo2.i, demo3.i, and demo4.i:
         demo1 - movies of sound and shock waves
         demo2 - movies of a drumhead oscillating
         demo3 - movie of a chaotic pendulum
         demo4 - visualization of the flow field around an airfoil
You can run a crude tutorial introducing all of the Yorick graphics commands by starting Yorick and typing:
         #include "testg.i"
         grtest
You can get a description of the various files in the interpreted library by typing (as a command to Yorick):
         library

Options

-i file.i

includes the Yorick source file file.i as Yorick starts. This is equivalent to the #include directive after Yorick has started.

-batch file.i

includes the Yorick source file file.i as Yorick starts. Your customization file custom.i, if any, is not read, and Yorick is placed in batch mode. Use the help command on the batch function (help, batch) to find out more about batch mode. In batch mode, all errors are fatal; normally, Yorick will halt execution and wait for more input after an error.

AUTHOR

David H. Munro, Lawrence Livermore National Laboratory

FILES

Y_SITE refers to the Yorick site directory; use the help command to find its name at your site (the variable Y_SITE also contains the name of the site directory):

Y_SITE/doc/*

documentation, including the quick reference sheets, user manual, and alphabetized collections of all the online help messages.

Y_SITE/i/*.i

a library of interpreted Yorick functions. Here are Bessel, gamma, and beta functions, multiple key sorting, curve fitting functions, and more. The file readme.i has a more complete description.

Y_SITE/g/*

graphics style sheets, palettes, and PostScript template

Y_SITE/i0/*.i

include files Yorick needs to read whenever it starts. Several of these contain the definitions of functions which you may need to read in order to fully understand their operation, or as examples of Yorick programs.

BUGS

If x is a scalar int, long, or double,
         x(1)= scalar-expression
will fail. You normally wouldn't do the assignment like this (you would just redefine x). Usually, you can work around this bug using the merge function; do "help, merge" and read Y_SITE/i/bessel.i for examples of the merge function.

Expressions like openb("file_containing_x").x do not work, even though they are syntactically and logically correct. It turns out the file closes before the data can be read. This one may be fixable, but it's not easy.

The nice= and restrict= keywords to the limits function don't seem to work properly.

Clipping of filled mesh plots (the plf command) is not always correct.

Text -- particularly curve markers -- is clipped by not drawing it; the absence of partial characters at the edge of a plot puzzles most people.

Recursive debug mode (debugging an error which occurred while you were debugging) doesn't work. Also, Yorick can't always get into and out of its debug mode properly. Occasionally, it will get the line number where an error occurred wrong, especially if the error was in the condition or increment clause of a for loop.

On pseudocolor displays, a color image may require you to move the mouse into yorick's X window to display properly, if you use the private=1 option of the window command. Unless your window manager allows you to set colormap focus independently of keyboard focus, this can be annoying.

SEE ALSO

gist(1)