[Scipy-tickets] [SciPy] #853: scipy.special.jv incorrect values for complex x & negative non-integer order

SciPy scipy-tickets@scipy....
Fri Jan 23 17:33:16 CST 2009


#853: scipy.special.jv incorrect values for complex x & negative non-integer
order
---------------------------+------------------------------------------------
 Reporter:  pv             |       Owner:  somebody
     Type:  defect         |      Status:  new     
 Priority:  high           |   Milestone:  0.8.0   
Component:  scipy.special  |     Version:  devel   
 Severity:  major          |    Keywords:          
---------------------------+------------------------------------------------
 Consider
 {{{
 >>> import scipy.special as sc
 >>> sc.jv(-0.5, 1),
 (0.4310988680183761
 >>> sc.jv(-0.5, 1+0j)
 (1.5305821969908724e-17+0.67139670714180366j)
 }}}
 The latter result is wrong, the former correct. However,
 {{{
 >>> sc.jv(-1, 1)
 -0.4400505857449335
 >>> sc.jv(-1, 1+0j)
 (-0.44005058574493355+5.3888874330650448e-17j)
 }}}
 I.e. the problem exists only for non-integer negative `v` and complex `x`.

 I think the problem lies in amos_wrappers.c:rotate -- I don't think the
 identity used there is valid for non-integer orders; the rotation is OK
 for the Hankel function, but not for the Re/Im parts of Bessel J.

-- 
Ticket URL: <http://scipy.org/scipy/scipy/ticket/853>
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