Source code in the octave programming language

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

saveimage("mandel.ppm", round(ms .* 255).', "ppm");

function z = mandelbrot()
    % to view the image call "image(mandelbrot())"
    width = 500; height = 500;
    z = zeros(width, height);
    c = zeros(width, height);

    xi = 1;
    for x = linspace(-2, 2, width)
        yi = 1;
        for y = linspace(-2, 2, height)
            c(yi, xi) = x+y*i; yi += 1;
        end
        xi += 1;
    end

    for iter = 1:50
        z = z.*z + c;
    end

    z = abs(z);
end