bugGNU Octave - Bugs: bug #35297, besseli returns incorrect results...

 
 

bug #35297: besseli returns incorrect results for negative integer orders

Submitted by:  Robert T. Short <rtshort>
Submitted on:  Thu 12 Jan 2012 05:11:38 PM UTC  
 
Category: LibrariesSeverity: 3 - Normal
Priority: 5 - NormalItem Group: Inaccurate Result
Status: FixedAssigned to: None
Originator Name: Robert T. ShortOpen/Closed: Closed
Release: 3.4.2Operating System: GNU/Linux

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Thu 12 Jan 2012 06:11:50 PM UTC, comment #1:

I checked in to changesets:

http://hg.savannah.gnu.org/hgweb/octave/rev/35ce1eab7400
http://hg.savannah.gnu.org/hgweb/octave/rev/ce731bb6a191

In the first, I mistakenly copied the part of the special case from zbesj that changed the sign of the result for odd negative orders. The second corrects that error.

The changes are on the stable branch, so the problem will be fixed in the upcoming 3.6.0 release.

John W. Eaton <jwe>
Project Administrator
Thu 12 Jan 2012 05:11:38 PM UTC, original submission:

In theory, besseli(n,x) = bessel(-n,x) when n is an integer.

In octave we get (for example)

octave:1> besseli(20,1),besseli(-20,1)
ans = 3.9668e-25
ans = -9.8143e+07

Robert T. Short <rtshort>

 

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    Follow 2 latest changes.

    Date Changed By Updated Field Previous Value => Replaced By
    Thu 12 Jan 2012 06:11:50 PM UTCjweStatusNone=>Fixed
      Open/ClosedOpen=>Closed

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