06 October 2025 01:24:20 AM

walker_sample_test():
  C version.
  Test walker_sample().

walker_sampler_test():
  walker_sampler() creates Walker sample vectors Y and A
  for efficient sampling of a discrete probability vector.
  Test the Walker sampler with a Zipf-type probability

  After 100 warmup calls, next 3 values of drand48():
  0.0876897
  0.347698
  0.517176

  Zipf probabilities
  for N = 10
  and parameter P = 2

     I     X[I]

     1 0.645258
     2 0.161314
     3 0.0716953
     4 0.0403286
     5 0.0258103
     6 0.0179238
     7 0.0131685
     8 0.0100822
     9 0.00796615
    10 0.00645258

  Randomly permuted X:

     I     X[I]

     1 0.00796615
     2 0.0258103
     3 0.645258
     4 0.0716953
     5 0.00645258
     6 0.0179238
     7 0.0100822
     8 0.161314
     9 0.0403286
    10 0.0131685

  Built the sampler
  i Y[i] A[i]:

    1 0.079661 3
    2 0.258103 3
    3 1.000000 3
    4 0.716953 3
    5 0.064526 3
    6 0.179238 3
    7 0.100822 8
    8 0.117253 3
    9 0.403286 8
   10 0.131685 3

  100000 samples:
  prob   #samples:

  0.007966    791
  0.025810   2598
  0.645258  64386
  0.071695   7252
  0.006453    641
  0.017924   1808
  0.010082    949
  0.161314  16201
  0.040329   4031
  0.013169   1343

  sumvar = 0.586454 (should be about 1)

  Verification sum = 1.11022e-16
  (Should be close to 0)

walker_sample_test():
  Normal end of execution.

06 October 2025 01:24:20 AM