[SciPy-dev] nbinom.ppf
Pierre GM
pgmdevlist at gmail.com
Mon Jul 27 15:47:44 EDT 2009
All,
I'm puzzled by this result:
>>> from scipy.stats.distributions import nbinom
>>> nbinom(.3,.15).ppf(nbinom(.3,.15).cdf(np.arange(20)))
array([ 1., 2., 2., 3., 5., 5., 6., 8., 9., 10., 11.,
12., 13., 14., 15., 16., 17., 18., 19., 20.])
I would have naturally expected np.arange(20).
Using np.round instead of np.ceil in nbinom_gen._ppf seems to solve
the issue.
Is there any reason not to do it ?
Thx in advance.
P.
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