[Scipy-tickets] [SciPy] #1471: stats.lognorm.pdf(0, s) reports nan

SciPy Trac scipy-tickets@scipy....
Wed Jul 13 17:30:32 CDT 2011


#1471: stats.lognorm.pdf(0,s) reports nan
-------------------------+--------------------------------------------------
 Reporter:  jaredd       |       Owner:  somebody   
     Type:  defect       |      Status:  new        
 Priority:  normal       |   Milestone:  Unscheduled
Component:  scipy.stats  |     Version:  0.9.0      
 Keywords:               |  
-------------------------+--------------------------------------------------

Comment(by jaredd):

 If scipy.stats wants to be a research-ready package, it should at least
 handle pdf and cdf values over the domain.  Considering the distributions
 module seems to work for most cases, refinement of the algos (particularly
 pdf/cdf) in the package for numerical stability seems like a logical next
 step.  Clearly the cases should be handled in the respective distribution
 classes, not in the parent classes.  In the case of the LN, a Taylor
 series poly may be appropriate for small values of x.  This would also
 ensure numerical accuracy for 0<=x<<1 as well.

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Ticket URL: <http://projects.scipy.org/scipy/ticket/1471#comment:2>
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