| 1 | .TH XScreenSaver 1 "08 Feb 2000" "X Version 11" |
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| 2 | .SH NAME |
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| 3 | critical - Draw a system showing self-organizing criticality |
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| 4 | .SH SYNOPSIS |
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| 5 | .B critical |
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| 6 | [\-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] |
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| 7 | .SH DESCRIPTION |
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| 8 | The \fIcritical\fP program displays a self-organizing critical system |
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| 9 | that gradually emerges from chaos. |
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| 10 | |
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| 11 | \fIcritical\fP performs a simulation on a two-dimensional array of |
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| 12 | integers. The array is initialized to random values. On each |
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| 13 | iteration, it draws a line to the array position with the greatest |
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| 14 | value. It then replaces that location and the eight neighboring |
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| 15 | locations with randomly-selected values. |
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| 16 | |
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| 17 | The lines are initially random, but over time a chaotic |
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| 18 | self-organizing system evolves: areas of the screen which happen to |
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| 19 | have lower values are less likely to be updated to new values, and so |
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| 20 | the line tends to avoid those areas. Eventually, the histogram of |
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| 21 | changes approaches the power-law curve typical of such systems. |
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| 22 | |
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| 23 | The simplest documented self-organizing system is the one-dimensional |
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| 24 | equivalent of \fIcritical\fP. |
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| 25 | |
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| 26 | I heard about this algorithm second-hand: apparently there was an |
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| 27 | article in \fIScientific American\fP describing it sometime in 1997. |
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| 28 | .SH OPTIONS |
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| 29 | .I critical |
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| 30 | accepts the following options: |
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| 31 | .TP 8 |
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| 32 | .B \-window |
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| 33 | Draw on a newly-created window. This is the default. |
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| 34 | .TP 8 |
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| 35 | .B \-root |
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| 36 | Draw on the root window. |
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| 37 | .TP 8 |
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| 38 | .B \-mono |
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| 39 | If on a color display, pretend we're on a monochrome display. |
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| 40 | .TP 8 |
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| 41 | .B \-install |
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| 42 | Install a private colormap for the window. |
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| 43 | .TP 8 |
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| 44 | .B \-visual \fIvisual\fP |
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| 45 | Specify which visual to use. Legal values are the name of a visual class, |
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| 46 | or the id number (decimal or hex) of a specific visual. |
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| 47 | .TP 8 |
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| 48 | .B \-delay \fIusecs\fP |
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| 49 | Number of microseconds to wait after drawing each line. |
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| 50 | .TP 8 |
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| 51 | .B \-random \fIboolean\fP |
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| 52 | Whether to use randomly selected colours rather than a cycle around |
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| 53 | the colour wheel. |
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| 54 | .TP 8 |
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| 55 | .B \-offset \fIinteger\fP |
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| 56 | The maximum random radius increment to use. |
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| 57 | .TP 8 |
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| 58 | .B \-ncolors \fIinteger\fP |
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| 59 | How many colors should be allocated in the color ramp (note that this |
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| 60 | value interacts with \fIoffset\fP.) |
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| 61 | .TP 8 |
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| 62 | .B \-trail \fIinteger\fP |
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| 63 | Length of the trail: between 5 and 100 is nice. |
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| 64 | .SH ENVIRONMENT |
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| 65 | .PP |
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| 66 | .TP 8 |
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| 67 | .B DISPLAY |
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| 68 | to get the default host and display number. |
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| 69 | .TP 8 |
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| 70 | .B XENVIRONMENT |
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| 71 | to get the name of a resource file that overrides the global resources |
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| 72 | stored in the RESOURCE_MANAGER property. |
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| 73 | .SH SEE ALSO |
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| 74 | .BR X (1), |
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| 75 | .BR xscreensaver (1) |
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| 76 | .BR xscreensaver-command (1) |
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| 77 | .BR xscreensaver-demo (1) |
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| 78 | .SH COPYRIGHT |
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| 79 | Copyright \(co 1998 by Martin Pool. |
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| 80 | |
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| 81 | Permission to use, copy, modify, distribute, and sell this software |
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| 82 | and its documentation for any purpose is hereby granted without fee, |
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| 83 | provided that the above copyright notice appear in all copies and that |
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| 84 | both that copyright notice and this permission notice appear in |
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| 85 | supporting documentation. No representations are made about the |
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| 86 | suitability of this software for any purpose. It is provided "as is" |
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| 87 | without express or implied warranty. |
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| 88 | .SH AUTHOR |
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| 89 | Martin Pool <mbp@humbug.org.au>, 1998-2000. Based in part on the |
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| 90 | XScreenSaver code by Jamie Zawinski <jwz@jwz.org>. |
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