www.pudn.com > NumericalComputingwithMatlabCode.zip > fern.m, change:2003-11-22,size:1237b

```function fern
%FERN  MATLAB implementation of the Fractal Fern
%   Michael Barnsley, Fractals Everywhere, Academic Press, 1993.
%   This version runs forever, or until stop is toggled.

shg
clf reset
'numbertitle','off','name','Fractal Fern')
x = [.5; .5];
h = plot(x(1),x(2),'.');
darkgreen = [0 2/3 0];
set(h,'markersize',1,'color',darkgreen,'erasemode','none');
axis([-3 3 0 10])
axis off
stop = uicontrol('style','toggle','string','stop', ...
'background','white');
drawnow

p  = [ .85  .92  .99  1.00];
A1 = [ .85  .04; -.04  .85];  b1 = [0; 1.6];
A2 = [ .20 -.26;  .23  .22];  b2 = [0; 1.6];
A3 = [-.15  .28;  .26  .24];  b3 = [0; .44];
A4 = [  0    0 ;   0   .16];

cnt = 1;
tic
while ~get(stop,'value')
r = rand;
if r < p(1)
x = A1*x + b1;
elseif r < p(2)
x = A2*x + b2;
elseif r < p(3)
x = A3*x + b3;
else
x = A4*x;
end
set(h,'xdata',x(1),'ydata',x(2));
drawnow
cnt = cnt + 1;
end
t = toc;
s = sprintf('%8.0f points in %6.3f seconds',cnt,t);
text(-1.5,-0.5,s,'fontweight','bold');
set(stop,'style','pushbutton','string','close','callback','close(gcf)')
```