This is a 982x810 256 color GIF of an image 
generated by a lyap program. The lyap 
program is available via anonymous ftp at 
ftp.uu.net (137.39.1.9) in 
/usenet/comp.sources.x/volume16/lyap 
as part01.Z and part02.Z.

It uses the algorithm described in the September 1991 Scientific American
to calculate and display a Lyapunov fractal.

This particular figure was calculated with the command :
lyap -f abbba -M -0.85 -a 3.813906 -w 0.050135 -b 3.815211 -h 0.049336

The coordinates of the figure are (3.813906, 3.864041) x (3.815211, 3.864546)
in a x b parameter space. The periodic forcing function (as described in
Scientific American) is abbba. A dwell of 400 and settle of 400 were used.
Initial condition was x=0.5 for all a and b.