Provided by: xscreensaver-data-extra_5.07-0ubuntu3_i386 bug
 

NAME

        critical - Draw a system showing self-organizing criticality
 

SYNOPSIS

        critical  [-display  host:display.screen]  [-foreground  color] [-back‐
        ground color] [-window] [-root]  [-mono]  [-install]  [-visual  visual]
        [-delay seconds] [-random boolean] [-ncolors int] [-offset int] [-fps]
 

DESCRIPTION

        The  critical  program  displays a self-organizing critical system that
        gradually emerges from chaos.
 
        critical performs a simulation on a two-dimensional array of  integers.
        The array is initialized to random values.  On each iteration, it draws
        a line to the array position with the greatest value.  It then replaces
        that  location  and  the  eight  neighboring  locations  with randomly-
        selected values.
 
        The lines are initially random, but over time a chaotic self-organizing
        system  evolves:  areas of the screen which happen to have lower values
        are less likely to be updated to new values, and so the line  tends  to
        avoid those areas.  Eventually, the histogram of changes approaches the
        power-law curve typical of such systems.
 
        The simplest documented self-organizing system is  the  one-dimensional
        equivalent of critical.
 
        I heard about this algorithm second-hand: apparently there was an arti‐
        cle in Scientific American describing it sometime in 1997.
 

OPTIONS

        critical accepts the following options:
 
        -window Draw on a newly-created window.  This is the default.
 
        -root   Draw on the root window.
 
        -mono   If on a color display, pretend we’re on a monochrome display.
 
        -install
                Install a private colormap for the window.
 
        -visual visual
                Specify which visual to use.  Legal values are the  name  of  a
                visual  class,  or the id number (decimal or hex) of a specific
                visual.
 
        -delay usecs
                Number of microseconds to wait after drawing each line.
 
        -random boolean
                Whether to use randomly selected colours rather  than  a  cycle
                around the colour wheel.
 
        -offset integer
                The maximum random radius increment to use.
 
        -ncolors integer
                How  many  colors  should  be allocated in the color ramp (note
                that this value interacts with offset.)
 
        -trail integer
                Length of the trail: between 5 and 100 is nice.
 
        -fps    Display the current frame rate and CPU load.
 

ENVIRONMENT

        DISPLAY to get the default host and display number.
 
        XENVIRONMENT
                to get the name of a resource file that  overrides  the  global
                resources stored in the RESOURCE_MANAGER property.
        X(1), xscreensaver(1) xscreensaver-command(1) xscreensaver-demo(1)
 

COPYRIGHT

        Copyright © 1998 by Martin Pool.
 
        Permission to use, copy, modify, distribute, and sell this software and
        its documentation for any purpose is hereby granted without  fee,  pro‐
        vided  that  the  above  copyright notice appear in all copies and that
        both that copyright notice and this permission notice  appear  in  sup‐
        porting documentation.  No representations are made about the suitabil‐
        ity of this software for any purpose.  It is provided "as  is"  without
        express or implied warranty.
 

AUTHOR

        Martin  Pool  <mbp@humbug.org.au>,  1998-2000.   Based  in  part on the
        XScreenSaver code by Jamie Zawinski <jwz@jwz.org>.