Math.atan()
The Math.atan()
static method returns the inverse tangent (in radians) of a number, that is
Try it
Syntax
js
Math.atan(x)
Parameters
x
-
A number.
Return value
The inverse tangent (angle in radians between
and
, inclusive) of x
. If x
is Infinity
, it returns
. If x
is -Infinity
, it returns
.
Description
Because atan()
is a static method of Math
, you always use it as Math.atan()
, rather than as a method of a Math
object you created (Math
is not a constructor).
Examples
Using Math.atan()
js
Math.atan(-Infinity); // -1.5707963267948966 (-ฯ/2)
Math.atan(-0); // -0
Math.atan(0); // 0
Math.atan(1); // 0.7853981633974483 (ฯ/4)
Math.atan(Infinity); // 1.5707963267948966 (ฯ/2)
// The angle that the line (0,0) -- (x,y) forms with the x-axis in a Cartesian coordinate system
const theta = (x, y) => Math.atan(y / x);
Note that you may want to avoid the theta
function and use Math.atan2()
instead, which has a wider range (between -ฯ and ฯ) and avoids outputting NaN
for cases such as when x
is 0
.
Specifications
Specification |
---|
ECMAScript Language Specification # sec-math.atan |
Browser compatibility
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