[Scipy-tickets] [SciPy] #748: scipy.stats.vonmises.pdf has discontinuous (and inaccurate) behaviour

SciPy scipy-tickets@scipy....
Wed Oct 8 17:11:50 CDT 2008


#748: scipy.stats.vonmises.pdf has discontinuous (and inaccurate) behaviour
---------------------+------------------------------------------------------
 Reporter:  peridot  |       Owner:  somebody
     Type:  defect   |      Status:  new     
 Priority:  normal   |   Milestone:          
Component:  Other    |     Version:          
 Severity:  normal   |    Keywords:          
---------------------+------------------------------------------------------
 he PDF has a switch at b=100, purely to ensure consistency with the (non-
 buggy) CDF (rather than accuracy).  This could pose a problem for fitting
 procedures, as the differences in likelihood (log PDF) are substantial:

 In [74]: np.log(scipy.stats.vonmises(99.999).pdf(-0.999*np.pi))
 Out[74]: -198.615121294

 In [75]: np.log(scipy.stats.vonmises(100).pdf(-0.999*np.pi))
 Out[75]: -491.110106535

 In [76]: np.log(scipy.stats.vonmises(100.001).pdf(-0.999*np.pi))
 Out[76]: -491.115026472

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Ticket URL: <http://scipy.org/scipy/scipy/ticket/748>
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