On Fri, 2013-06-07 at 18:53 +1000, Benjamin Herrenschmidt wrote:
> +
> +static double crackpot_sqrt(double val)
> +{
> + int i;
> + float x, y;
> + const float f = 1.5F;
> +
> + x = val * 0.5F;
> + y = val;
> + i = * ( int * ) &y;
> + i = 0x5f3759df - ( i >> 1 );
> + y = * ( float * ) &i;
> + y = y * ( f - ( x * y * y ) );
> + y = y * ( f - ( x * y * y ) );
> + return val * y;
> +}
> +
For those interested, this is the Quake3 sqrt from Carmack ... there's
plenty of literature about it one or two google clicks away :-)
Cheers,
Ben.
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