package mymath
import "math"
func InvSqrt(x float32) float32 {
var xhalf float32 = 0.5*x // get bits for floating VALUE
i := math.Float32bits(x) // gives initial guess y0
i = 0x5f375a86 - (i>>1) // convert bits BACK to float
x = math.Float32frombits(i) // Newton step, repeating increases accuracy
x = x*(1.5-xhalf*x*x)
x = x*(1.5-xhalf*x*x)
x = x*(1.5-xhalf*x*x)
return 1/x
}
