2. D. The Moran Equation

Derivation of the Moran Equation

We need to rewrite the similarity dimension formula

ds = Log(N)/Log(1/r)

so the scaling factors (each is r in the cases to which this formula can be applied) can be separated from one another. Then we could change the individual values of r into different values ri.

Writing d = ds,

d = Log(N)/Log(1/r)

can be rewritten as

dLog(1/r) = Log(N)

Pulling the d inside the Log

Log((1/r)d) = Log(N)

and exponentiating both sides

(1/r)d = N

That is,

1 = N*rd

and so

1 = rd + ... + rd

where we have one r for each of the N copies of the fractal in the decomposition.

Replacing each copy of r with ri, we see the similarity dimension d must satisfy

1 = r1d + ... + rNd.

This is the Moran equation.

So long as each of the ri satisfies 0 < ri < 1, the Moran equation has a unique solution, and that solution is the similarity dimension d = ds.

Return to Moran Equation.