Bryan J. Smith wrote:
> On Mon, 2004-10-11 at 02:49, Robert Snyder wrote:
>
>>I dont see it passing any -O3 commands to the compilier. As I watch it
>>go passing by.
>>The defualt cflags for Portage when compiling are "-O2 -march=pentium4
>>-fomit-frame-pointer" Now I have noticed when using a gui front end like
>>porthole that at the bottom they do list additional flags that the
>>piticular ports mantainer decided to use extra usually you see thing
>>like mmx and sse flags but never seen the -O3
>
>
> Okay, maybe the package offers SSE support.
>
> That's fine for gaming, but for scientific/engineering, do _not_ use SSE
> on a Pentium 3/4! Trust me on this.
>
>
>>But things are stable and "FEEL" slightly faster. I will emphansize
>>"FEEL" because I have no hard proof that it is faster.
>
>
> If SSE is being liberally used where it shouldn't, which I've seen a few
> packages do not, then I don't doubt it.
>
> You should _never_ use SSE for double-precision floating-point on a
> Pentium 3/4 when you need accuracy. It's lossy and inaccurate by a
> significant number of digits.
>
> The P3/4 SSE pipes were designed to be fast, not accurate.
> Most people don't know this until they get major error in a calculation.
>
I'm probably opening a can of worms I shouldn't by asking this, but:
What is SSE? I know what the FPU is, but you lost me with SSE.
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