OT : Approximate / fast math libraries ?

[Mike McCarty]

Chris Jones wrote:
> On Friday 31 August 2007 5:50:36 pm Rex Dieter wrote:
> 
>>Chris Jones wrote:
[snip]
>>gcc -ffast-math
> 
> 
> Yes, I tried that but it didn't seem to make as much difference as I had hoped 
> it would...

If the math package is written at all well, then you aren't going
to speed it up by lowering the precision, as you are already getting
hardware boost. The Intel architecture (I presume that's what you
are using) includes hardware computation of logs etc. For example,
there is a single instruction FPATAN which does an arctangent.
Writing some code to do a truncated series with lower precision
is going to be SLOWER.

Mike
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