In most cases, xn
will converge to a root of f
While most people learn this using real functions, there is no reason
why Newton's Method cannot be used with complex functions. So,
given a function f
) with multiple
roots, we can color each point z
in the complex plane by which root Newton's Method will converge to if z0
We can also alter the color depending on how quickly we
converge to the root, and we will color the point black if we don't
converge to anything in a predetermined number of steps.
Since this is an iterative complex system, it is not too surprising
that we end up with fractals. What is wonderful about this scheme is the
great variety of images one can make with this simple concept.
The students in my numerical analysis class were given a
program that would create these fractals. They picked the
function, the colors, and the error tolerance. Some of the
results are listed below.
If you would like to try the program: newton2.nb
. You need
Mathematica to run it. If you create a picture that you are
particularly proud of, send me the code and I'll include it