Fast Inverse Square Root

Fast inverse square root explained

    float InvSqrt(float x){
        float xhalf = 0.5f * x;
        int i = *(int*)&x;            // store floating-point bits in integer
        i = 0x5f3759df - (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;
    }

Source: betterexplained.com

Fast Inverse Square Root

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;
}

Source: en.wikipedia.org

Similar codes

26 votes113 views10 answers
Bootstrap
C++
17 votes154 views4 answers
How to reference a child gameobject unity
C++
-1 vote119 views1 answer
React cookie
C++
3 votes120 views2 answers
Find kth max and min element in an array
C++
0 vote131 views1 answer
Cpp set time
C++
9 votes131 views4 answers
Max c++
C++
2 votes131 views1 answer
C++ wait for user input
C++
0 vote121 views1 answer
How to check private messages on reddit
C++
21 votes130 views6 answers
Random in c++
C++
2 votes126 views2 answers
Anagram
C++