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Re: [Help-gsl] a new wrapper for the GSL

From: Robin Hankin
Subject: Re: [Help-gsl] a new wrapper for the GSL
Date: Fri, 19 Nov 2004 14:30:01 +0000

Dear Brian, and List

thanks for this.   Which brings me to my next point.

While coding up the wrapper, I found having A&S by my side to be very reassuring,
in that I could verify that everything worked.  For example, I would test the
Airy functions (see the following short R session):

R> airy_Ai(0.5)
[1] 0.2316936064808335

and see directly that this matches the bottom left hand number of table 10.11 on page 475.

Now,  I think it would be a very good idea to have this kind of information for
EVERY function in the special functions part of the reference book. This would give people the opportunity to "spot check" their work. I would have found this very helpful.

My idea is to include an appendix that would start out like this:

airy_Ai(0.5) = 0.2316936064808335
airy_Ai_scaled(0.5) = 0.2932771591299473
airy_Bi(0.5) = 0.8542770431031556
airy_Bi_scaled(0.5) = 0.6748924111156303

(or how about putting a line like this under each function description?)

Note that it's of limited use to report special values such as sin(0)=0, which are not
good diagnostics.  "Random" values are much better.

I would be very happy to produce such an appendix, if the community thinks it is a good idea.

Graphs would also be possible, which might be even better for developers.

What do the collected GSL gurus think?

Robin Hankin writes:
 > I have written an "R" wrapper for the special functions of the GSL.
 > The R language and GSL wrapper (named "gsl") is available at

Thanks! I've added a link in the "Wrappers for other Languages"
section of the GSL webpage.

Brian Gough

Network Theory Ltd,
Commercial support for GSL ---

Robin Hankin
Uncertainty Analyst
Southampton Oceanography Centre
SO14 3ZH
tel +44(0)23-8059-7743
address@hidden (edit in obvious way; spam precaution)

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