Inverse Square

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

0 vote128 views2 answers
Add variable to legend matlab
C++
2 votes141 views1 answer
Disable a warning in visual c++
C++
-2 votes139 views1 answer
How to iterate through array in c++
C++
13 votes140 views6 answers
Cin in c++
C++
1 vote146 views1 answer
How to loop a 2 dimensional vector in c++ starting from second element
C++
2 votes266 views1 answer
Lopping over an array c++
C++
0 vote128 views2 answers
Change colour of output to terminal c++
C++
15 votes134 views4 answers
How to make a random number in c++
C++
0 vote131 views1 answer
Age in days in c++
C++
1 vote154 views1 answer
C++ check if string contains non alphanumeric
C++