# JavaScript | Math.log1p()

The Math.log1p() is an inbuilt function in JavaScript which gives the value of natural logarithm of 1 + p number. Natural logarithm is of base e, where e is an irrational and transcendental number approximately equal to 2.718.
Syntax:

`Math.log1p(1 + p)`

Parameters:

• In parameter 1+p, p is any number whose natural logarithm of base e is being calculated.
• Return Values:

• It returns the value of base e of logarithm of any number added with 1.

Examples:

```Input:
Math.log1p(5)
Output:
1.791759469228055```

Explanation:
Here value of natural logarithm of number 5 is 1.791759469228055 as shown output.

```Input:
Math.log1p(10)
Output:
2.3978952727983707
```

Let’s see some JavaScript code on this function:

Code #1:

 ` `

Output:

```6.90875477931522
2.5649493574615367
3.295836866004329
1.791759469228055```

Code #2:

 ` `

Output:

```0.6931471805599453
1.6094379124341003
2.0794415416798357
2.3978952727983707
2.639057329615259
2.833213344056216
2.995732273553991
```
Errors and exceptions:

1. Parameters for this function should always be a number otherwise it returns NaN i.e, not a number when its parameter is taken as a string.
 ` `

Output:

``` NaN
```
2. This function gives error when its parameter is taken as complex number because it accepts only integer value as the parameter.
 ` `

Output:

```Error: Invalid or unexpected token
```
3. This function returns NaN i.e, not a number if the parameter is less than -1 because number should be any positive number i.e, greater then 0.
 ` `

Output:

``` NaN
```

Application:

• Whenever we need to find the value of natural logarithm of 1 + p number that time we take the help of this function. Its value needed many times in mathematics problem.
Let’s see JavaScript code for this application:
Code #1:

 ` `

Output:

`1.146128035678238`