Henon Mapping
This Henon mapping is an area-preserving map of the plane given by
x(n+1) = x(n)cos(t) - (y(n)-x(n)^2)sin(t)
y(n+1) = x(n)sin(t) + (y(n)-x(n)^2)cos(t)
In this program you type in a decimal multiple of pi between 0 and 1
and the program plots 50 orbits in different colors. A tiny change in
the angle can change the character of the orbits; for example try
.5 and then try .51.
For more on this see the article "Henon Mapping with Pascal" by Gordon
Hughes (BYTE Magazine, Dec. 1986).