[Scipy-tickets] [SciPy] #1647: BUG: stats: _argcheck function for the erlang distribution is misnamed.

SciPy Trac scipy-tickets@scipy....
Sat May 5 11:17:56 CDT 2012


#1647: BUG: stats: _argcheck function for the erlang distribution is misnamed.
------------------------------+---------------------------------------------
 Reporter:  warren.weckesser  |       Owner:  somebody    
     Type:  defect            |      Status:  needs_review
 Priority:  normal            |   Milestone:  Unscheduled 
Component:  scipy.stats       |     Version:  0.10.0      
 Keywords:                    |  
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Comment(by josefpktd):

 Are there any actual use cases for an integer parameter restricted
 distribution?
 Nothing prevents users from only using integer values for the parameter.

 practicality beats purity (or something like that)

 I don't see it being worth the trouble, having to sometimes special case
 erlang in a loop over all distributions, and coming up with an integer
 constraint estimation.

 If there are actual use cases or computational advantages, then I agree
 that the change would be useful, but so far I don't see any.

 (one possible computational argument from the history of the distribution
 could be that it was easier to calculate the factorial instead of gamma.
 But factorial doesn't work for larger numbers. I just fixed a problem with
 poisson in statsmodels replacing factorial by gammaln, and we increase the
 use of gamma and gammaln in stats.distributions in the last years because
 it's more precise.)

-- 
Ticket URL: <http://projects.scipy.org/scipy/ticket/1647#comment:8>
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