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From: Ludovic Brenta <ludovic@ludovic-brenta.org>
Newsgroups: comp.lang.ada
Subject: Re: Where I find Bessel function for Ada ?
Date: Wed, 26 Nov 2008 08:12:21 -0800 (PST)
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Date: 2008-11-26T08:12:21-08:00
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On Nov 26, 4:09 pm, Ken Thomas <k...@ecs.soton.ac.uk> wrote:
> On Nov 26, 1:08 pm, Paul Cole Gloster <Colin_Paul_Glos...@ACM.org>
> wrote:
>
>
>
> > Reinert submitted:
>
> > |----------------------------------------------------------------|
> > |"I want to use the modified Bessel function of order 0 in my Ada|
>
> > |program.                                                        |
>
> > |                                                                |
>
> > |Where I find it ?"                                              |
> > |----------------------------------------------------------------|
>
> > It may be best to write your own version so that you could justifiably
> > have an accurate level of confidence of it.
>
> > Gautier responded:
>
> > !---------------------------------------------------------------!
> > !"It is in the Numerical Recipes in Pascal, chapter 6.4, pp 191.!
>
> > !All you need to pick the right Pascal source, like bessj0.pas  !
>
> > !and put it through th P2Ada translator:http://p2ada.sf.net/ !
>
> > !The NR sources are freely available on the Internet."          !
> > !---------------------------------------------------------------!
>
> > I have not thoroughly assessed that particular part of "Numerical
>
> > Recipes", but some parts of "Numerical Recipes" are
> > untrustworthy. Early in 2009 on
> > WWW.ACCU.org
> > a review by myself which is almost ready for publication should be
> > available.
>
> The source for the Pascal version of Numerical Recipes can be found athttp://archives.math.utk.edu/software/msdos/numerical.analysis/nrpas1...
>
> As the code for bessj0 is very short, translation to Ada is a small
> exercise. On the other hand, the code seems to deal with only single
> precision arithmetic so does not promise high accuracy.

I suppose this is easy to fix by making the Ada implementation
generic. The user then instantiates it for any floating-point type
with the required accuracy.

--
Ludovic Brenta.