On Sep 29, 2009, at 4:36 PM, Greg Ewing wrote:

> Chris Colbert wrote:
>
>> over 6x improvement just by avoid a few measly pow statements...
>> anyone know why i'm stuck in slowpow?
>
> Using pow to calculate x**2 is always going to be slower
> than x*x, no matter how smart the pow function is. Function
> calls have some overhead, even in C.

The pow function is a builtin, so it can be really "smart."  
Interestingly, I just tested and pow(x, n) is optimized away for  
n=-1, 0, 1, and 2. (gcc 4.0.1) giving the obvious code for those four  
cases.

- Robert

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