OT : Approximate / fast math libraries ?

[Les]

On Fri, 2007-08-31 at 15:48 +0100, Chris Jones wrote:
> Hi,
> 
> I have a number crunch application that is starting to hit bottlenecks 
> in standard maths functions, like log, exp sqrt etc. Thing is, in many 
> places I don't need much precision, so was wondering if there was 
> anything I could do, like use a different library or enable some gcc 
> options (currently using -O2) to speed things up.
> 
> Does anyone have any recommendations for fast maths ? search around on 
> the web I've found a lot of references to fast / approximate math 
> libraries, but nothing obvious.
> 
> Chris
> 
Numerical Recipes in C (they also exist in other languages, but this is
the one I use) from Cambridge.  I think many of the algorithms are on
line.  There are also some libraries available from NASA that are public
domain.

Regards,
Les H