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+.TH XScreenSaver 1 "08 Feb 2000" "X Version 11"
+.SH NAME
+critical - Draw a system showing self-organizing criticality
+.SH SYNOPSIS
+.B critical
+[\-display \fIhost:display.screen\fP] [\-foreground \fIcolor\fP] [\-background \fIcolor\fP] [\-window] [\-root] [\-mono] [\-install] [\-visual \fIvisual\fP] [\-delay \fIseconds\fP] [\-random \fIboolean\fP] [\-ncolors \fIint\fP] [\-offset \fIint\fP] 
+[\-fps]
+.SH DESCRIPTION
+The \fIcritical\fP program displays a self-organizing critical system
+that gradually emerges from chaos.
+
+\fIcritical\fP 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 \fIcritical\fP.
+
+I heard about this algorithm second-hand: apparently there was an
+article in \fIScientific American\fP describing it sometime in 1997.
+.SH OPTIONS
+.I critical
+accepts the following options:
+.TP 8
+.B \-window
+Draw on a newly-created window.  This is the default.
+.TP 8
+.B \-root
+Draw on the root window.
+.TP 8
+.B \-mono 
+If on a color display, pretend we're on a monochrome display.
+.TP 8
+.B \-install
+Install a private colormap for the window.
+.TP 8
+.B \-visual \fIvisual\fP
+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.
+.TP 8
+.B \-delay \fIusecs\fP
+Number of microseconds to wait after drawing each line.
+.TP 8
+.B \-random \fIboolean\fP
+Whether to use randomly selected colours rather than a cycle around
+the colour wheel.
+.TP 8
+.B \-offset \fIinteger\fP
+The maximum random radius increment to use.
+.TP 8
+.B \-ncolors \fIinteger\fP
+How many colors should be allocated in the color ramp (note that this
+value interacts with \fIoffset\fP.)
+.TP 8
+.B \-trail \fIinteger\fP
+Length of the trail: between 5 and 100 is nice.
+.TP 8
+.B \-fps
+Display the current frame rate and CPU load.
+.SH ENVIRONMENT
+.PP
+.TP 8
+.B DISPLAY
+to get the default host and display number.
+.TP 8
+.B XENVIRONMENT
+to get the name of a resource file that overrides the global resources
+stored in the RESOURCE_MANAGER property.
+.SH SEE ALSO
+.BR X (1),
+.BR xscreensaver (1)
+.BR xscreensaver-command (1)
+.BR xscreensaver-demo (1)
+.SH COPYRIGHT
+Copyright \(co 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,
+provided that the above copyright notice appear in all copies and that
+both that copyright notice and this permission notice appear in
+supporting documentation.  No representations are made about the
+suitability of this software for any purpose.  It is provided "as is"
+without express or implied warranty.
+.SH AUTHOR
+Martin Pool <mbp@humbug.org.au>, 1998-2000.  Based in part on the
+XScreenSaver code by Jamie Zawinski <jwz@jwz.org>.