[Scipy-tickets] [SciPy] #623: scipy.special.jv incorrect for certain argument(s)

SciPy scipy-tickets@scipy....
Fri Apr 18 16:06:35 CDT 2008


#623: scipy.special.jv incorrect for certain argument(s)
-------------------------------+--------------------------------------------
 Reporter:  wa03               |        Owner:  cookedm 
     Type:  defect             |       Status:  assigned
 Priority:  high               |    Milestone:  0.7     
Component:  scipy.special      |      Version:          
 Severity:  major              |   Resolution:          
 Keywords:  special.jv bessel  |  
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Comment (by wernerg):

 Re: faddeeva function w(z) (related to erfc)
 Does it make sense to handle the Im(z)<0 case as well?

 I've attached code that I wrote to do that; it's very similar
 to cef.py, but handles Im(z)<0 (attached faddeeva.py; also
 included is a function that graphs the difference between results
 for w(z) using different numbers of N.  I'd suggest using a default
 of N=42 (or not much greater than 40), rather than 100; the relative
 difference between results with N=40 and higher N seem to be less than
 1e-14.  And differences between N=100 and higher N are still less than
 1e-14, so increasing to N=100 doesn't really help much.

 On another note, if a special function doesn't handle a certain case
 (such as Im(z)<0), would it be better to raise an exception?  I would
 prefer that, to help me avoid errors in my work.

 Thanks,
 Greg.

-- 
Ticket URL: <http://scipy.org/scipy/scipy/ticket/623#comment:7>
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