The Mandelbrot Set and Julia Sets

Julia Sets - Computational Issues

Accuracy vs. time

However, suppose all of z0, ..., z100 lie within a distance of 2 from the origin.
Can we conclude the sequence never runs away to infinity?
Unfortunately not: maybe z200 will be farther than 2 from the origin.
Now we must make a choice. Select some maximum number, N, of iterations we are willing to try.
If all of z0, ..., zN lie within a distance of 2 from the origin, we assert the sequence will never run away to infinity and so z0 belongs to Kc.
This leaves open the possibility that we incorrectly conclude some points belong to Kc.
For example, here are two renderings of Kc (the points painted black) for the same c. On the left, N = 10; on the right, N = 50.
Generally, the larger N, the fewer mistakes we make. On the other hand, the larger N, the more computer time needed to generate the picture.

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