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1 module math
2 
3 // q_sqrt computes an approximation of the inverse square root (1 / √x) using a fast
4 // inverse square root algorithm. This method is often used in applications
5 // where performance is crucial, such as in computer graphics or physics
6 // simulations.
7 // (This algorithm is inspired by the famous "fast inverse square root" code
8 // used in the Quake III Arena game engine.)
9 @[inline]
10 pub fn q_rsqrt(x f64) f64 {
11     x_half := 0.5 * x
12     mut i := i64(f64_bits(x))
13     i = 0x5fe6eb50c7b537a9 - (i >> 1)
14     mut j := f64_from_bits(u64(i))
15     j *= (1.5 - x_half * j * j)
16     j *= (1.5 - x_half * j * j)
17     return j
18 }
19

1	module math
2
3	// q_sqrt computes an approximation of the inverse square root (1 / √x) using a fast
4	// inverse square root algorithm. This method is often used in applications
5	// where performance is crucial, such as in computer graphics or physics
6	// simulations.
7	// (This algorithm is inspired by the famous "fast inverse square root" code
8	// used in the Quake III Arena game engine.)
9	@[inline]
10	pub fn q_rsqrt(x f64) f64 {
11	x_half := 0.5 * x
12	mut i := i64(f64_bits(x))
13	i = 0x5fe6eb50c7b537a9 - (i >> 1)
14	mut j := f64_from_bits(u64(i))
15	j = (1.5 - x_half j * j)
16	j = (1.5 - x_half j * j)
17	return j
18	}
19