Mandelbrot set: Difference between revisions

=={{header|GNU Octave}}==

This code runs rather slowly and produce coloured Mandelbrot set by accident (output image [http://i43.tinypic.com/zlp252.jpg here]).

<lang matlab>#! /usr/bin/octave -qf

global width = 200;

global height = 200;

maxiter = 100;

z0 = 0;

global cmax = 1 + i;

global cmin = -2 - i;

function cs = pscale(c)

global cmax;

global cmin;

global width;

global height;

persistent px = (real(cmax-cmin))/width;

persistent py = (imag(cmax-cmin))/height;

cs = real(cmin) + px*real(c) + i*(imag(cmin) + py*imag(c));

endfunction

ms = zeros(width, height);

for x = 0:width-1

for y = 0:height-1

z0 = 0;

c = pscale(x+y*i);

for ic = 1:maxiter

z1 = z0^2 + c;

if ( abs(z1) > 2 ) break; endif

z0 = z1;

endfor

if ( ic == maxiter )

ms(x+1, y+1) = 1.0;

else

ms(x+1, y+1) = ic/maxiter;

endif

endfor

endfor

saveimage("mandel.ppm", round(ms .* 255).', "ppm");</lang>