Christopher James Huff wrote:
> 
> You mean for helping the compiler detect something that can be
> vectorized and doing it automatically? It won't pick out the possibility
> in the one-line version?
> Would it get this version?
> DBL value = 0;
> value += sin(EPoint[0]);
> value += sin(EPoint[1]);
> value += sin(EPoint[2]);
> return Sqr(value/3.0);

No, unfortunately the Intel compiler (the only one that I have which does 
vectorisation) does not recoginze this. You explicitly have to use a loop. 
I have done rewriting vector.h in such a way. But I have no Pentium4 to 
test it :( 

> I'm not surprised the for loop wasn't used in the existing
> version...SIMD stuff wasn't even a factor, so of course the code wasn't
> designed for it, and compilers probably weren't good enough at
> optimizing to get rid of the for() loop.

Todays g++ 3.1 does a good job in loop-unrolling. But with my modified 
loop-using 'vector.h' it does still produce a slightly slower code (OK, 
maybe I have also made some mistakes in the converting..)

- Micha 

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