Homework 9
Math 323, Fall 2012
Due Date: Thursday, November 29
1. Consider the following iterated function system on the square [0, 1]2 :
PP
P
P
P
−→
Find formulas for the four maps of this system, and use Mathematica to plot 10,000
points in a typical orbit. What is the attractor for this system?
2. The iterated function system above can be used to construct the Hilbert curve. The
first few stages of the construction of this curve are shown below:
Stage 1
Stage 2
Stage 3
Stage 4
Use Mathematica to plot stages 5, 6, 7, and 8 of the Hilbert curve. You should use a
Line to plot the curve, and a second Line to draw the boundary square, combining
them with the Graphics command.
3. For each n, let γn : [0, 1] → [0, 1]2 be a constant-speed parametrization of the nth stage
of the Hilbert curve, starting in the lower left.
(a) Find a piecewise formula for γ1 (t).
(b) Find formulas for γn (0) and γn (1) in terms of n.
4. Let γ : [0, 1] → [0, 1]2 be the function defined by
γ(t) = lim γn (t).
n→∞
Then γ is a continuous fractal curve whose image is the entire unit square [0, 1]2 .
(a) What are γ(0) and γ(1)? Explain.
(b) Determine the locations of γ(1/3), γ(2/3), γ(1/4), γ(1/2), and γ(3/4).
(c) Use Mathematica to determine the location of γ(1/5). Express the coordinates of
your answer as fractions.
5. Use Mathematica to find the value of t for which γ(t) = (1/3, 1/3). (You might find the
Nearest and Position commands helpful for this.) Express your answer as a fraction.