>> Is integer addition faster or slower than floating-point addition?
> 
>   Impossible to say. It depends on the processor type, the integrity of
> the pipelines, the combination of instructions, and tons of other things.
> 
>   If you are measuring purely the clock cycles taken by one single addition,
> disregarding everything else, then they are probably equally fast (although
> with modern Intel/AMD processors I cannot even say that for sure, as they
> have microcodes which take fractions of a clock cycle and weirdness like
> that).

Interesting. I have always heard that floating-point arithmetic is much 
slower than integer arithmetic. (That's why they invented the FPU, but 
it's still slower.) So you're saying they're actually roughly the same 
speed now?

>> How about multiplication?
> 
>   It depends on the processor. Some processors have 1-clock-cycle FPU
> multiplication, while others don't. Some have special circuitry for
> calculating CPU register multiplication in 1 clock cycle, others have
> a small fraction of that circuitry which calculates it in 2 or a few
> clock cycles, and yet others calculate it with the FPU (which curiously
> makes integer multiplication slower than floating point multiplication).

 From one table I saw, integer multiplication is significantly slower 
than integer addition, and integer division is markedly slower again. I 
don't know if the same holds for floating-point though, or how fast/slow 
floating-point arithmetic is compared to integer arithmetic in general.

>> How do trigonometric functions compare?
> 
>   What do you think?

I think they're slower, but how much? 2x slower? 20,000x slower? I have 
no idea.

>> Is single precision any faster than double precision?
> 
>   Only if we measure with the pipeline and cache capacity requirements.
> 
>> Are 8-bit integers faster than 16-bit integers?
> 
>   It depends on the processor.

OK, cool. So basically there is no way I can tell whether implementing 
an algorithm one way or the other will yield the best speed. Yay, me. :-/

-- 
http://blog.orphi.me.uk/
http://www.zazzle.com/MathematicalOrchid*

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