OT : Approximate / fast math libraries ?

Mike McCarty Mike.McCarty at sbcglobal.net
Tue Sep 4 23:17:27 UTC 2007


Matthew Saltzman wrote:
> On Sat, 2007-09-01 at 09:41 -0500, Michael Hennebry wrote:
> 
> 
>>How much precision do you need?  On what? Why?
>>
>>At least one person wrote a book on implementing the C standard library.
>>It would probably be a better resource than Numerical Recipes.
> 
> 
> That would be PJ Plauger's The Standard C Library, Prentice Hall, 1992
> 0-13-131509-9.  Most of his math lib implementation is based on Cody and
> Waite, Software Manual for the Elementary Functions, Prentice Hall, 1980
> (sorry, he doesn't give the ISBN).  

My copy of Cody & Waite is ISBN 0-13-822064-6. The exact title
is "Software Manual for the Elementary Functions".

I'm afraid I'm not very impressed with "Numerical Recipes".
I bought a copy many years ago, and found some humorous lapses
in the multi-precision FFT based math package. Things which
proved that they don't know what they are doing, I'm afraid.
Like subtracting one float from another repeatedly in a loop
instead of using fmod().

I've had good results with Cody & Waite, though it's getting
somewhat dated (1980) and some better stuff has come along,
or so I've heard.

But, if the hardware is being used, then coding something with
less accuracy is also going to be slower.

Mike
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