Reverse 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

10 votes283 views2 answers
Check if character in string c++
C++
2 votes312 views2 answers
C++ check palindrome
C++
3 votes317 views4 answers
C++ char array size
C++
2 votes310 views1 answer
Unordered_map of pair and int
C++
1 vote319 views1 answer
Print 5 table in c++
C++
0 vote348 views1 answer
Equalize problem codeforces
C++
1 vote304 views1 answer
C++ power
C++
9 votes315 views4 answers
Print vector c++
C++
0 vote364 views1 answer
How to analyse a poem
C++
0 vote329 views1 answer
C++ formatting
C++