Returns an integer matrix (of class Mandelbrot) with
non-negative counts.
Arguments
Z
A complex matrix for which convergence
counts should be calculated.
xmid, ymid, side, resolution
Alternative specification of
the complex plane Z, where
mean(Re(Z)) == xmid,
mean(Im(Z)) == ymid,
diff(range(Re(Z))) == side,
diff(range(Im(Z))) == side, and
dim(Z) == c(resolution, resolution).
maxIter
Maximum number of iterations per bin.
tau
A threshold; the radius when calling
divergence (Mod(z) > tau).
Author
The internal Mandelbrot algorithm was inspired by and
adopted from similar GPL code of Martin Maechler available
from ftp://stat.ethz.ch/U/maechler/R/ on 2005-02-18 (sic!).