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

SciPy scipy-tickets@scipy....
Fri Oct 3 09:34:59 CDT 2008


#623: scipy.special.jv incorrect for certain argument(s)
-------------------------------+--------------------------------------------
 Reporter:  wa03               |        Owner:  cookedm 
     Type:  defect             |       Status:  assigned
 Priority:  normal             |    Milestone:  0.7.0   
Component:  scipy.special      |      Version:          
 Severity:  major              |   Resolution:          
 Keywords:  special.jv bessel  |  
-------------------------------+--------------------------------------------
Changes (by oliphant):

  * priority:  high => normal

Comment:

 I've added a "hack" fix in r4765 which special-cases the jv(3,4)
 discontinuity.   The problem for that combination is in the recur function
 in the jv.c file.

 The iteration starts of with pk = qk = 32 when n=3 and x=4.  This is a
 special-case of the recursion where t=0 after the first iteration, but the
 result is in-correct.   More study is needed to determine what is going
 wrong and if special-casing n=3 and x=4 is the right long-term solution.

-- 
Ticket URL: <http://scipy.org/scipy/scipy/ticket/623#comment:8>
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