Fast inverse square root

The Fast Inverse Square Root is an algorithm that estimates the inverse square root of a floating-point number with great speed and relatively low accuracy. It became widely known after being used in the video game Quake III Arena for real-time rendering, where performance was critical. The key advantage of this algorithm is its use of bit manipulation and clever approximations to provide an estimate of the inverse square root, which is \(\frac{1}{\sqrt{x}}\).