gallery/graphs/mandel.py

   1 # contributed by Stephen Phillips
   2
   3 from pyx import *
   4
   5 # Mandelbrot parameters
   6 re_min = -2
   7 re_max = 0.5
   8 im_min = -1.25
   9 im_max = 1.25
  10 gridx = 100
  11 gridy = 100
  12 max_iter = 10
  13
  14 # Set-up
  15 re_step = (re_max - re_min) / gridx
  16 im_step = (im_max - im_min) / gridy
  17 d = []
  18
  19 # Compute fractal
  20 for re_index in range(gridx):
  21     re = re_min + re_step * (re_index + 0.5)
  22     for im_index in range(gridy):
  23         im = im_min + im_step * (im_index + 0.5)
  24         c = complex(re, im)
  25         n = 0
  26         z = complex(0, 0)
  27         while n < max_iter and abs(z) < 2:
  28             z = (z * z) + c
  29             n += 1
  30         d.append([re - 0.5 * re_step, re + 0.5 * re_step,
  31                   im - 0.5 * im_step, im + 0.5 * im_step,
  32                   float(n)/max_iter])
  33
  34 # Plot graph
  35 g = graph.graphxy(height=8, width=8,
  36                   x=graph.axis.linear(min=re_min, max=re_max, title=r'$\Re(c)$'),
  37                   y=graph.axis.linear(min=im_min, max=im_max, title=r'$\Im(c)$'))
  38 g.plot(graph.data.list(d, xmin=1, xmax=2, ymin=3, ymax=4, color=5),
  39        [graph.style.rect(color.gradient.Rainbow)])
  40 g.dodata() # plot data first, then axes
  41 g.writeEPSfile('mandel')
  42 g.writePDFfile('mandel')