[Scipy-tickets] [SciPy] #869: stats.invnorm.cdf returns NaNs with low mu values

SciPy scipy-tickets@scipy....
Sun Feb 15 04:00:05 CST 2009


#869: stats.invnorm.cdf returns NaNs with low mu values
-------------------------+--------------------------------------------------
 Reporter:  jpaalasm     |       Owner:  somebody
     Type:  defect       |      Status:  new     
 Priority:  normal       |   Milestone:  0.8.0   
Component:  scipy.stats  |     Version:  devel   
 Severity:  normal       |    Keywords:          
-------------------------+--------------------------------------------------
 When the value of the parameter mu is low, which means that variance/mean
 ratio is low, stats.invnorm.cdf returns !NaNs.

 {{{
 In [149]: import scipy.stats

 In [150]: x = scipy.arange(0.0015, 0.0025, 0.0001)

 In [151]: mu = 0.002

 In [152]: scipy.stats.invnorm.pdf(x, mu).tolist()
 Out[152]:
 [6.1513646267771192e-06,
  0.023229992417723441,
  7.6072744186245522,
  324.80877031930538,
  2494.937154192151,
  4460.3102903819281,
  2285.9804058215414,
  398.33010537152063,
  27.167634400261772,
  0.8155911803011362]

 In [153]: scipy.stats.invnorm.cdf(x, mu).tolist()
 Out[153]: [nan, nan, nan, nan, nan, nan, nan, nan, nan, nan]
 }}}

-- 
Ticket URL: <http://scipy.org/scipy/scipy/ticket/869>
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