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

23 votes108 views1 answer
How to declare a function in c++
C++
0 vote135 views1 answer
C++ fill array with 0
C++
2 votes101 views1 answer
Replace a char in string c++ at a specific index
C++
0 vote104 views1 answer
How to signify esc key in cpp
C++
1 vote112 views2 answers
Cpp substring
C++
1 vote118 views1 answer
Pass c++
C++
0 vote96 views1 answer
How to store pair in min heap in c++
C++
1 vote105 views1 answer
Double to float c++
C++
1 vote117 views4 answers
C++ pause
C++
1 vote106 views1 answer
Modulo Exponentiaon,Iteratve Modulo Exponentiation
C++