[Scipy-tickets] [SciPy] #1842: wrong value returned by scipy.stats.binom probability mass function when true probability is 1

SciPy Trac scipy-tickets@scipy....
Mon Feb 11 18:31:12 CST 2013


#1842: wrong value returned by scipy.stats.binom probability mass function when
true probability is 1
-------------------------+--------------------------------------------------
 Reporter:  leflage      |       Owner:  rgommers   
     Type:  defect       |      Status:  new        
 Priority:  normal       |   Milestone:  Unscheduled
Component:  scipy.stats  |     Version:  0.11.0     
 Keywords:               |  
-------------------------+--------------------------------------------------

Comment(by josefpktd):

 Thanks for reporting,

 The distributions still have problems with 0 * log(0) at several places,
 and they are not always easy to find.

 We still don't have a general solution, so it needs to be special cased.
 The ``if`` doesn't work, however, because the function needs to work for
 vector/array arguments.
 I think we use a mask in other places, like

 mask = ((p == 1) & (k == n)) | ((p == 0) & (k == 1))
 and then conditionally assign.

 (It's nicer than using np.where because it avoids the calculation that
 raises a warning.)

 Do you want to volunteer for a pull request?

-- 
Ticket URL: <http://projects.scipy.org/scipy/ticket/1842#comment:1>
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