#17678: special values of Bessel functions
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       Reporter:  rws                |        Owner:
           Type:  enhancement        |       Status:  needs_review
       Priority:  minor              |    Milestone:  sage-6.5
      Component:  symbolics          |   Resolution:
       Keywords:                     |    Merged in:
        Authors:  Ralf Stephan       |    Reviewers:
Report Upstream:  N/A                |  Work issues:
         Branch:                     |       Commit:
  u/rws/special_values_of_bessel_functions|  
191ca289d3c26813e0244251a983a62f2057347a
   Dependencies:                     |     Stopgaps:
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Comment (by rws):

 Replying to [comment:6 kcrisman]:
 > Question: [http://www.wolframalpha.com/input/?i=besselj%28-5%2F2%2C0%29
 W|A claims] that one has the complex infinity, not positive infinity, for
 some of the negative ones like `bessel_J(-5/2, 0)` or for `bessel_I`.  I
 don't know what to make of that, though.
 I got those values from mpmath and just tried to post about that to the
 mpmath group, but not yet approved.
 > Also, does `bessel_Y` have an analogous special value for x=0, negative
 n?
 Ah, I missed that. It should be easily derived from `Bessel_J` with
 Y,,n,,(z)=(J,,n,,(z)*cos(n*pi)-J,,-n,,(z))/sin(n*pi) (Abramowitz and
 Stegun 1972, p. 358).

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Ticket URL: <http://trac.sagemath.org/ticket/17678#comment:7>
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