#include <stdio.h>

float Q_rsqrt( float number )
{
	long i;
	float x2, y;
	const float threehalfs = 1.5F;
 
	x2 = number * 0.5F;
	y  = number;
	i  = * ( long * ) &y;                       // evil floating point bit level hacking
	i  = 0x5f3759df - ( i >> 1 );               // what the fuck?
	y  = * ( float * ) &i;
	y  = y * ( threehalfs - ( x2 * y * y ) );   // 1st iteration
      y  = y * ( threehalfs - ( x2 * y * y ) );   // 2nd iteration, this can be removed
 
	return y;
}

int main(void) {
	printf("%f\n", 1.0f/Q_rsqrt(144.0f)); // 12
	printf("%f\n", 1.0f/Q_rsqrt(289.0f)); // 17
	printf("%f\n", 1.0f/Q_rsqrt(25472209.0f)); // 5047
	printf("%f\n", 1.0f/Q_rsqrt(95775582.25f)); // 9786,5
	return 0;
}