#include <stdio.h>
#include <math.h>
 
float f(float n) {
    n = 1.0f / n;
    long i;
    float x, y;
 
    x = n * 0.5f;
    y = n;
    i = *(long *)&y;
    i = 0x5f3759df - (i >> 1);
    y = *(float *)&i;
    y = y * (1.5f - (x * y * y));
 
    return y;
}
 
int main(void) {
	int n = 4, x[] = {4, 64, 10000, 2};
	float r, s, d;
 
	for (int i = 0; i < n; i++) {
		r = f(x[i]);
		s = sqrtf(x[i]);
		d = fabsf((fabsf(r) - s) / s) * 100.0f;
		printf("%d\t%f\t%f\t%f\n", x[i], r, s, d);
	}
 
	return 0;
}

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