JavaScript Math atan()

In this tutorial, you will learn about the JavaScript Math.atan() method with the help of examples.

The atan() method calculates the arctangent (inverse of tangent) of the specified angle and returns it.


let num = Math.atan(1);
//Output: 0.7853981633974483

atan() Syntax

The syntax of the atan() method is:


Here, atan() is a static method. Hence, we are accessing the method using the class name, Math.

atan() Parameter

The atan() method takes a single parameter:

  • angle - in radians whose arctangent value is calculated

atan() Return Value

The atan() method returns:

  • arctangent value of the angle argument
  • NaN (Not a Number) if x is a non-numeric value

Note: The returned angle will always be in the range -π/2 to π/2 for numeric arguments.

Example 1: JavaScript Math.atan()

// compute arctangent of 0 let number1 = Math.atan(0);
// compute arctangent of -5 let number2 = Math.atan(-5);
console.log(number2); // Output: // 0 // -1.373400766945016

In the above example,

  • Math.atan(0) - calculates the arctangent of 0
  • Math.atan(-5) - calculates the arctangent of -5

Example 2: Math.atan() with Infinity

// atan() with positive infinity let number1 = Math.atan(Infinity);
// atan() with negative infinity let number2 = Math.atan(-Infinity)
; console.log(number2); // Output: // 1.5707963267948966 (π/2) // -1.5707963267948966 (-π/2)

Here the math.atan() method calculates the arctangent of infinity. As you can see, the output value is still between -π/2 and π/2.

Example 3: Math.atan() with a Non-Numeric Argument

// string variables
let string = "Dwayne"

// atan() with string arguments let result = Math.atan(string);
console.log(result); // Output: NaN

In the program above, we have used a string argument, Dwayne with atan(). In this case, we get NaN as output.

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