JavaScript Math atan()

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

atan() Syntax

The syntax of the atan() method is:

Math.atan(angle)

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);
console.log(number1);  

// 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);
console.log(number1); 

// 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.

Recommended readings:

• JavaScript Math tan()
• JavaScript Math asin()