JavaScript Math.log1p()

// calculate ln(1+p) of 1 which is equivalent to ln(2)
var value = Math.log1p(1); // ln(2)

console.log(value);
 
// Output: 0.6931471805599453

log1p() Syntax

The syntax of the log1p() method is:

Math.log1p(x)

Here, log1p() is a static method. Hence, we need to access the method using the class name, Math.

log1p() Parameters

The log1p() method takes in:

• x - a number

log1p() Return Values

The log1p() method returns:

• natural logarithm (base e) of (1+ given number).
• NaN for negative numbers and non-numeric arguments.

Example 1: JavaScript Math.log1p()

// find the base e log value of 1 + 1
var value1 = Math.log1p(1);

console.log(value1); 

// find the base e log value of 1 + 8
var value2=Math.log1p(8);

console.log(value2)

// find the base 2 log value of 1 + 5
var value3 = Math.log1p(5);

console.log(value3); 

Output

0.6931471805599453
2.1972245773362196
1.791759469228055

In the above example,

• Math.log1p(1) - computes the base e log value of 1 + 1
• Math.log1p(8) - computes the base e log value of 1 + 8
• Math.log1p(5) - computes the base e log value of 1 + 5

Example 2: log1p() With 0

 
// find the base e log value of 1 + 0
var value = Math.log1p(0);

console.log(value);

// Output:  0

In the above example, we have used the log1p() method to compute the base e log value of 1 + 0.

The output 0 represents that the base e log value of 1 + 0 is 0.

Example 3: log1p() With Negative Values

// find the base e log value of -1
var value = Math.log(-1);

console.log(value); 

// Output:  NaN

In the above example, we have used the log() method to compute the base e log value of a negative number.

The output NaN stands for Not a Number. We get this result because the base e log value of negative numbers is undefined.

Recommended Readings:

• JavaScript Math.log()
• JavaScript Math.exp()