Provided by: xscreensaver-data_5.36-1ubuntu1_amd64 
NAME
xlyap - display an array of Lyapunov exponents graphically
SYNOPSIS
xlyap [-BLps][-W width][-H height][-o filename][-a n ] [-b n ] [-w n ] [-h n ] [-i xstart]
[-M n ] [-R p ] [-S n ] [-D n ] [-F string][-f string][-r n ] [-O n ] [-C n ] [-c
n ] [-m n ] [-x xpos] [-y ypos]
[-fps]
DESCRIPTION
xlyap generates and graphically displays an array of Lyapunov exponents for a variety of
iterated periodically forced non-linear maps of the unit interval.
OPTIONS
-random A good choice for use with xscreensaver: picks random parameters from a built-in
list.
-C n Specifies the minimum color index to be used for negative exponents
-D n Specifies the "dwell" or number of iterations over which to average in order to
calculate the Lyapunov exponent. Default is 50.
-H n Specifies the height of the window. Default is 256.
-L Indicates use log(x) + log(y) rather than log(xy).
-M r Specifies the real value to compare exponent values to for indexing into a color
wheel. The default value is 1.0.
-O n Specifies the minimum color index to be used for positive exponents
-R p Specifies pseudo-random forcing with probability p of using parameter value 'a'.
-S n Specifies the "settle" or number of iterations prior to the beginning of the
calculation of the Lyapunov exponent. Default is 50.
-a r Specifies the real value to use as the minimum parameter value of the horizontal
axis. Default is 2.0 for the logistic map.
-b n Specifies the real value to use as the minimum parameter value of the vertical
axis. Default is 2.0 for the logistic map.
-c n Selects one of six different color wheels to use. The default color wheel is a
rainbow palette.
-F 10101010
Specifies the "Function" forcing function to use. The example above would
alternate between iterating the circle and logistic maps. An argument of "-F 2323"
would alternate between left and right logistic maps. The default is to only use
the single specified map (see the description of -m).
-f abbabaab
Specifies the forcing function to use. The default is to alternate between the "a"
parameter and the "b" parameter.
-h r Specifies the real value to be used as the range over which the vertical parameter
values vary. The default is 1.0.
-i r Specifies the real value of the initial condition to use. Default is 0.65.
-m n Selects between available non-linear maps of the unit interval. A value of 0
specifies the logistic map. A value of 1, the circle map. A value of 2, the left-
logistic. A value of 3, the right-logistic. A value of 4, the double-logistic. The
default is 0, the logistic map.
-o filename
Specifies the output filename to be used. If the -o option is given, this file
will automatically be written out at the completion of the drawing. If it is not
specified, a default filename of lyap.out is used and only written if the 'f' or
'F' keys are pressed during a run. The format of the output file is PPM for color
and PGM for monochrome. The parameters used to calculate the picture are included
as comments at the beginning of the output file.
-p Switches color indices for negative and positive exponents. Generally, causes
negative exponents to be displayed in more detail while darkening and narrowing
the color range for positive exponents. This can be toggled during runtime by
pressing the 'p' key.
-r n Specifies the maximum rgb value to be used. Default is 65000.
-s n Specifies the length of the color wheel spin.
-v Prints out the various values to be used and exits.
-w r Specifies the real value to be used as the range over which the horizontal
parameter values vary. The default is 1.0.
NOTES
During display, pressing any mouse button allows you to select the area to be investigated
with the mouse. The upper left hand corner of the desired area is the location of the
cursor when the button is pressed. The lower right hand corner is specified by the cursor
when the button is released.
Use of the keys bBeEfFkKjJmnrRsSwWxXqQ indicates:
(<) Halve dwell value.
(>) Double dwell value.
([) Halve settle value.
(]) Double settle value.
(B or b) Toggle button display on/off
(E or e) Recalculate the indices into the color wheel using a different method
(F or f) Save current screen to output file (not yet implemented)
(H or h or ?) Display brief help message
(i) Decrement the interval between stripes for the striped color map.
(I) Increment the interval between stripes for the striped color map.
(K) Decrease value exponents are compared against by 0.05.
(J) Increase value exponents are compared against by 0.05.
(M) Decrease value exponents are compared against by 0.005.
(N) Increase value exponents are compared against by 0.005.
(m) Increment the map index, changing the map to be iterated.
(P or p) Toggle positive/negative exponent display.
(r) Redraw the window using previously calculated exponents.
(R) Redraw the window using the newly set dwell and/or settle values.
(S) Spin the color wheel
(s) Halve the length of the spin and spin the color wheel
(u) Go up to the window just prior to the most recent zoom.
(U) Go all the way up to the original window.
(V or v) Display values of various parameters currently in use
(W or w) Use next color map.
(X or x) Clear window
(Q or q) quit
AUTHOR
Ronald Joe Record
The Santa Cruz Operation
P.O. Box 1900
Santa Cruz, CA 95061
rr@sco.com
ACKNOWLEDGEMENTS
The algorithm was taken from the September 1991 Scientific American article by A. K.
Dewdney who gives credit to Mario Markus of the Max Planck Institute for its creation.
Additional information and ideas were gleaned from the discussion on alt.fractals
involving Stephen Hall, Ed Kubaitis, Dave Platt and Baback Moghaddam. Assistance with
colormaps and spinning color wheels and X was gleaned from Hiram Clawson. Rubber banding
code was adapted from an existing Mandelbrot program written by Stacey Campbell.
Viciously hacked for xscreensaver by Jamie Zawinski, 20-Nov-97.