go/src/math/atan2.go

// Atan2 returns the arc tangent of y/x, using
// the signs of the two to determine the quadrant
// of the return value.
//
// Special cases are (in order):
//
//	Atan2(y, NaN) = NaN
//	Atan2(NaN, x) = NaN
//	Atan2(+0, x>=0) = +0
//	Atan2(-0, x>=0) = -0
//	Atan2(+0, x<=-0) = +Pi
//	Atan2(-0, x<=-0) = -Pi
//	Atan2(y>0, 0) = +Pi/2
//	Atan2(y<0, 0) = -Pi/2
//	Atan2(+Inf, +Inf) = +Pi/4
//	Atan2(-Inf, +Inf) = -Pi/4
//	Atan2(+Inf, -Inf) = 3Pi/4
//	Atan2(-Inf, -Inf) = -3Pi/4
//	Atan2(y, +Inf) = 0
//	Atan2(y>0, -Inf) = +Pi
//	Atan2(y<0, -Inf) = -Pi
//	Atan2(+Inf, x) = +Pi/2
//	Atan2(-Inf, x) = -Pi/2
func Atan2(y, x float64) float64 { … }

func atan2(y, x float64) float64 { … }