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

6 votes254 views2 answers
What is heap buffer overflow
C++
2 votes294 views2 answers
How to clear screen in C++ console
C++
1 vote252 views1 answer
Add element to start of vector c++
C++
17 votes324 views4 answers
Max element in vector c++
C++
0 vote305 views1 answer
Rotation 2d d'un point
C++
0 vote307 views1 answer
C++ compile to exe
C++
0 vote324 views1 answer
Result += a +b in c++ meaning
C++
0 vote291 views1 answer
How to check if vector is ordered c++
C++
0 vote326 views1 answer
Assignment of single field in struct in solidity
C++
0 vote331 views1 answer
2d array of zeros c++
C++