Python C extension to compute the permanent.
Du kan inte välja fler än 25 ämnen Ämnen måste starta med en bokstav eller siffra, kan innehålla bindestreck ('-') och vara max 35 tecken långa.

47 lines
1.3KB

  1. import os, sys
  2. import time
  3. import multiprocessing as mp
  4. import numpy as np
  5. import time
  6. from matplotlib import pyplot as plt
  7. from permanent import permanent
  8. def perm_ryser(a):
  9. ''' the permanent calculated using the ryser formula. much faster than the naive approach '''
  10. n,n2=a.shape
  11. z=np.arange(n)
  12. irange=xrange(2**n)
  13. get_index=lambda i: (i & (1 << z)) != 0
  14. get_term=lambda index: ((-1)**np.sum(index))*np.prod(np.sum(a[index,:], 0))
  15. indeces=map(get_index, irange)
  16. terms=map(get_term, indeces)
  17. return np.sum(terms)*((-1)**n)
  18. maxtime=1
  19. dimensions=range(1,11)
  20. for (function, label) in zip((permanent, perm_ryser), ("C", "Python")):
  21. counts=[]
  22. for dimension in dimensions:
  23. print dimension
  24. real=np.random.uniform(-1, 1, dimension*dimension).reshape((dimension, dimension))
  25. imag=np.random.uniform(-1, 1, dimension*dimension).reshape((dimension, dimension))
  26. submatrix=real+1j*imag
  27. t=time.clock()
  28. n=0
  29. while time.clock()-t < maxtime:
  30. for i in range(5):
  31. function(submatrix)
  32. n+=5
  33. counts.append(n)
  34. plt.plot(dimensions, counts, '.-', label=label)
  35. plt.ylabel('Number of permanents per second')
  36. plt.xlabel('Dimension')
  37. plt.xlim(min(dimensions), max(dimensions))
  38. plt.legend()
  39. plt.semilogy()
  40. plt.savefig('out.pdf')