On Mon, Oct 27, 2003 at 03:39:21PM +0000, William Chesters wrote:
> And that's an improvement over
> 
>     double pow(double x, int n) {
>       double it = 1;
>       while (--n >= 0) it *= x;
>       return it;
>     }
> 
>     double pow3(double x, int n) {
>       return pow(x, 3);
>     }
> 
> in what way exactly?  (If it doesn't work for you, try
> -funroll-all-loops.)

And that's an improvement over

template <int N>
inline double pow (double x) {
  return x * pow<N-1>(x);
}
template<>
inline double pow<0> (double x) {
  return 1.0;
}

in what way exactly?  (If it doesn't work for you, try 
-O2) :)

The C example relies on a fairly smart compiler to 
do interprocedual analysis.  The C++ example 
only requires the inline keywork be honored, and you 
don't need explicit pow3 pow2, you have pow<3> pow<2> 
pow<any constant>.

Gives a bit more control over code generation.

Andrew

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