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Dynamics of holomorphic transformations; Mandelbrot and Julia sets.

7 votes
Accepted

Examples of cubic Julia sets

As Lasse suggests, you can draw pictures of the parameter space to help you explore the possible dynamic behavior of cubic polynomials. Any cubic polynomial is conjugate to some polynomial of the for …
Mark McClure's user avatar
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7 votes
Accepted

Newton method and Siegel disks

Implementing Alexandre's suggestion, I found that for $\lambda\approx 0.483096 + 1.00504\ i$, we have $$ \begin{align} P_{\lambda}(z) &= (z - 1)\ (z + 1/2 - \lambda)\ (z + 1/2 + \lambda) \\ &\approx …
Mark McClure's user avatar
  • 2,083
13 votes

Convergence of Newton's method

I don't think your initial assertion is accurate. Consider, for example, $f(z)=z^5-z-1$. If you iterate the Newton's method function $N(z) = z-f(z)/f'(z)$ from $z_0=0$, you'll quickly find an attracti …
Mark McClure's user avatar
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6 votes

A question about Julia set for quadratic family

Joe's answer and the cited paper are, indeed, quite nice. I think the basic idea is fairly self-contained and probably easier than the reference. Two complex polynomials $f$ and $g$ of the same degre …
Mark McClure's user avatar
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1 vote

Linearizing a power series by conjugation

I think it is very unusual for the $h_n$s to have a simpler formulation. Even in the case of a quadratic polynomial, the conjugating function $h$ need not be a polynomial. I'm afraid I don't have a ge …
Mark McClure's user avatar
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4 votes

Is there a effective computational criterion to all periodic points of a rational function a...

As Alexandre points out, if every critical point of a rational function is pre-periodic, then the Julia set of the function is the entire Riemann sphere. This is stated as Theorem 4.3.1 in Beardon's …
Mark McClure's user avatar
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27 votes

Why are the Julia sets so simple? (quadratic family)

Julia sets are all very closely related to self-similar sets - each one can be thought of as the invariant set of something like an iterated function system. Specifically, the Julia set of $f(z)=z^2 + …
Mark McClure's user avatar
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14 votes

Rounding errors in images of Julia sets

Computer generated images of Julia sets tend to agree strongly with theory so we expect there must be some reason. I believe there are two main forces at work that generally mitigate the problem of r …
Mark McClure's user avatar
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4 votes
Accepted

Periodicity in iterated powers of sin, cos, exp

In spite of the potential issues arising from the fact that this function is not entire, there is a standard way to describe the components that you see in these types of pictures. Suppose that we are …
Mark McClure's user avatar
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