[Scipy-tickets] [SciPy] #503: bug in special function iv for large argumen

SciPy scipy-tickets@scipy....
Sat Jan 24 12:00:30 CST 2009


#503: bug in special function iv for large argumen
---------------------------+------------------------------------------------
 Reporter:  mbakker7       |        Owner:  somebody
     Type:  defect         |       Status:  reopened
 Priority:  normal         |    Milestone:  0.8.0   
Component:  scipy.special  |      Version:          
 Severity:  normal         |   Resolution:          
 Keywords:                 |  
---------------------------+------------------------------------------------
Changes (by pv):

  * status:  closed => reopened
  * resolution:  fixed =>

Comment:

 Not completely fixed yet: simultaneous large `v` and large `x` yield NaNs:
 {{{
 >>> import scipy.special as sc
 >>> sc.iv(1200, 1300)
 nan
 }}}

 Moreover, for `v = -1/2, -3/2, ...`, Cephes tries to evaluate `hyperg` at
 a singularity:
 {{{
 >>> sc.iv(-0.5, 1)
 0.0
 >>> sc.iv(-0.5 + 1e-13, 1)
 1.2312002145930347
 }}}

-- 
Ticket URL: <http://scipy.org/scipy/scipy/ticket/503#comment:5>
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