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Re: List of constants.


From: David Bateman
Subject: Re: List of constants.
Date: Sat, 10 Feb 2007 12:52:34 +0100
User-agent: Thunderbird 1.5.0.7 (X11/20060921)

Muthiah Annamalai wrote:
>> Muthiah Annamalai wrote:
>>> Hello there,
>>>
>>> I was looking for some physical constant (Boltzmann Constant K),
>>>  lately, and thought if we had some inbuilt thing in Octave
>>> (Octave-Forge) like the table from NIST, at
>>> http://www.physics.nist.gov/cuu/Constants/Table/allascii.txt
>>> it could be quite useful.
>>>
> 
> On Fri, 2007-02-09 at 10:58 -0500, Tom Holroyd (NIH/NIMH) [E] wrote:
>> you could make a constant package.
>>
> I have uploaded a copy of physical-constants in the octave-forge/main/
> CVS. I think someone can have a look at it, and suggest improvements.
> 
> A list of constants is at,
> http://octave.cvs.sourceforge.net/octave/octave-forge/main/
> physical-constants/test-consts.m?revision=1.1&view=markup
> 
> A functions are at, 
> http://octave.cvs.sourceforge.net/octave/octave-forge/main/
> physical-constants/inst/
> 
> ~ Muthiah

Muthu,

I think it might be better to store the NIST data and a script to create
the functions. This might be in the sub-directory src/ with a script and
Makefile to built the functions. This allows new functions to be
automatically added by updating the database and repackaging.

Also I'm not sure its a great idea to have a function for each constant,
 as you increase the chances of a collision with one of the users
functions. I think I'd prefer a function that took a string argument,
converted to lower case and found the minimum unique matching string and
returned the matching constant. That is

c = physical_constant("SpeedOf")

would match "speedoflight", but if both "speedoflight" and
"speedofunladenpigeon" were defined

c = physical_constant("SpeedOf")

should throw an error as an ambiguous request for a constant. In any
case this is just a preference of how I would implement this if I was
doing it..

D.



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