package bloob

import "math"

func FastSin(x float64) float64 {
	const PI = 3.14159265358979323846264338327950288
	const INVPI = 0.31830988618379067153776752674502872
	const A = 0.00735246819687011731341356165096815
	const B = -0.16528911397014738207016302002888890
	const C = 0.99969198629596757779830113868360584

	k := int32(math.Round(INVPI * x))
	x -= float64(k) * PI
	x2 := x * x
	x = x * (C + x2*(B+A*x2))
	if k%2 != 0 {
		x = -x
	}
	return x
}

func FastCos(x float64) float64 {
	return FastSin(x + math.Pi/2)
}