Lyap is a Vista DEM landscape generator for portions of Lyapunov Space.
For more details on Lyapunov Space, see the September 1991 issue of
Scientific American, Mathematical Recreations section. To run Lyap, you
need to specify a Vista Landscape filename, an 'a' and 'b' value
(between -3.5 and 0), a divisor (258.0 covers a width of exactly 1.0,
a larger divisor covers a smaller area, and a smaller one a larger
area.), a scale factor to make the function values come out as reasonable
elevations, a pattern of which values to iterate with, and a number of
iterations. An iteration value of 1 takes about 3 minutes with Lyap.881
on an Amiga 3000/25mhz. A value of 200 takes about 6 hours. The value
used in the Scientific American article would take days to compute.
Although smaller values will not give the spectacular images shown in the
Scientific American article, they do create rather extrordinary landscapes
in their own right. To start off with, I recommend the command line:

1>Lyap test.scape -2.8 -2.8 133.0 100.0 aaabaaa 10

which will produce an unusual landscape. Varying the 'a' and 'b' values
will move around in the scape, and you can focus in on a given area by
increasing the divisor. The larger the iteration value, the smaller you
will want to make the scaling factor. This is not that important, as you
can rescale the landscape from within VistaPro.

This program is Copyright © 1991 by Virtual Reality Laboratories, Inc.
Permission is granted by the above to freely copy and distribute this
program as long as this ReadMe file is included with the distribution.

For those who want to mess with the source, it is written in SAS 'C'.
Place the Amiga.h and Lyap.h files in the same directory as Lyap.c.

lc -O -f8 -Lm881 Lyap.c --- For 68030/68881 operation
lc -O -Lm Lyap.c --- For generic 68000 operation.