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CIS_mandelMPI.py

calcpage Feb 16th, 2013 1,645 Never
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  1. def mandelbrot(x, y, maxit):
  2.     c = x + y*1j
  3.     z = 0 + 0j
  4.     it = 0
  5.     while abs(z) < 2 and it < maxit:
  6.         z = z**2 + c
  7.         it += 1
  8.     return it
  9.  
  10. x1, x2 = -2.0, 1.0
  11. y1, y2 = -1.0, 1.0
  12. w, h = 150, 100
  13. maxit = 127
  14.  
  15. from mpi4py import MPI
  16. import numpy
  17.  
  18. comm = MPI.COMM_WORLD
  19. size = comm.Get_size()
  20. rank = comm.Get_rank()
  21.  
  22. # number of rows to compute here
  23. N = h // size + (h % size > rank)
  24.  
  25. # first row to compute here
  26. start = comm.scan(N)-N
  27.  
  28. # array to store local result
  29. Cl = numpy.zeros([N, w], dtype='i')
  30.  
  31. # compute owned rows
  32.  
  33. dx = (x2 - x1) / w
  34. dy = (y2 - y1) / h
  35. for i in range(N):
  36.     y = y1 + (i + start) * dy
  37.     for j in range(w):
  38.         x = x1 + j * dx
  39.         Cl[i, j] = mandelbrot(x, y, maxit)
  40.  
  41. # gather results at root (process 0)
  42.  
  43. counts = comm.gather(N, root=0)
  44. C = None
  45. if rank == 0:
  46.     C = numpy.zeros([h, w], dtype='i')
  47.  
  48. rowtype = MPI.INT.Create_contiguous(w)
  49. rowtype.Commit()
  50.  
  51. comm.Gatherv(sendbuf=[Cl, MPI.INT],recvbuf=[C, (counts, None), rowtype],root=0)
  52.  
  53. rowtype.Free()
  54.  
  55. if comm.rank == 0:
  56.     from matplotlib import pyplot
  57.     pyplot.imshow(C, aspect='equal')
  58.     pyplot.spectral()
  59.     pyplot.show()
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