evandrix/invsqrt.c

## invsqrt.c
float InvSqrt(float x){
   float xhalf = 0.5f * x;
   int i = *(int*)&x; // store floating-point bits in integer
   i = 0x5f3759d5 - (i >> 1); // initial guess for Newton's method
   x = *(float*)&i; // convert new bits into float
   x = x*(1.5f - xhalf*x*x); // One round of Newton's method
   return x;
}
	float InvSqrt(float x){
	float xhalf = 0.5f * x;
	int i = (int)&x; // store floating-point bits in integer
	i = 0x5f3759d5 - (i >> 1); // initial guess for Newton's method
	x = (float)&i; // convert new bits into float
	x = x(1.5f - xhalfx*x); // One round of Newton's method
	return x;
	}