atan2 (JavaScript)

Gets the inverse tangent of an angle using two parameters.

Defined in

Syntax

atan2(y:double,
x:double)
: double


Parameter	Description
`y`	The side of a right triangle adjacent to an angle. See below for special cases.
`x`	The side of a right triangle opposite to the same angle. See below for special cases.


Return value	Description
`double`	The inverse tangent of `y/x` in radians. See rad (JavaScript) to convert degrees to radians.

Usage

Special cases are as follows:

The following yields NaN: y or x is NaN.
The following yield +0:
- y is +0 and x is positive
- y is positive and finite and x is +Infinity
The following yield -0:
- y is -0 and x is positive
- y is negative and finite and x is +Infinity

The following yield pi:
- y is +0 and x is negative
- y is positive and finite and x is -Infinity
The following yield -pi:
- y is -0 and x is negative
- y is negative and finite and x is -Infinity
The following yield pi/2:
- y is positive and x is 0
- y is +Infinity and x is finite
The following yield -pi/2:
- y is negative and x is 0
- y is -Infinity and x is finite
The following yields pi/4: y and x are +Infinity.
The following yields 3*pi/4: y is +Infinity and x is -Infinity.
The following yields -pi/4: y is -Infinity and x is +Infinity.
The following yields -3*pi/4: y and x are -Infinity.

The following are equivalent: atan(y/x) and atan2(y, x).

Examples

This button onclick event calculates an angle in degrees of a right triangle given the length of the adjacent side and the length of the opposite side.

sessionScope.angleA = 
	Math.deg(Math.atan2(sessionScope.a, sessionScope.b))