[Scipy-tickets] [SciPy] #1740: Large-argument Bessel functions are wrong

SciPy Trac scipy-tickets@scipy....
Wed Oct 3 14:03:55 CDT 2012


#1740: Large-argument Bessel functions are wrong
------------------------------+---------------------------------------------
 Reporter:  AndreasKloeckner  |       Owner:  pv         
     Type:  defect            |      Status:  new        
 Priority:  normal            |   Milestone:  Unscheduled
Component:  scipy.special     |     Version:  0.11.0     
 Keywords:                    |  
------------------------------+---------------------------------------------
Changes (by pv):

  * owner:  somebody => pv
  * component:  Other => scipy.special


Comment:

 Bad heuristics in Cephes once again, jv.c:135 seems to be to blame as the
 branch for y > n/2 produces correct results.

 The aim is of course to compute special functions to ULP accuracy, not to
 relative or absolute tolerances.

 The easiest fix is probably to throw this piece of Cephes code away, and
 take a working implementation from Boost.

-- 
Ticket URL: <http://projects.scipy.org/scipy/ticket/1740#comment:1>
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