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:

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<script>
  
// Different numbers are being taken
// as the parameter of the function.
document.write(Math.log1p(1000) + "<br>");
document.write(Math.log1p(12) + "<br>");
document.write(Math.log1p(26) + "<br>");
document.write(Math.log1p(5));
  
</script>

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Output:

6.90875477931522
2.5649493574615367
3.295836866004329
1.791759469228055

Code #2:

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<script>
  
// Taken parameter from 1 to 19 incremented by 3.
for (i = 1; i < 20; i += 3)
{
    document.write(Math.log1p(i) + "<br>");
}
  
</script>

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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.
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    <script>
      
        // Parameters for this function should always be a
        // number otherwise it return NaN i.e, not a number
        // when its parameter taken as string.
        document.write(Math.log1p("gfg"));
      
    </script>

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    Output:

     NaN
    
  2. This function gives error when its parameter is taken as complex number because it accepts only integer value as the parameter.
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    <script>
      
        // Parameters can never be a complex number because
        // it accept only integer value as the parameter.
        document.write(Math.log1p(1 + 2i));
      
    </script>

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    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.
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    <script>
      
        // This function return 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.
        document.write(Math.log1p(-2));
      
    </script>

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    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:

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    <script>
      
        // taking parameter as number 14 and calculated
        // in the form of function.
        function value_of_base_e_logarithms_of_any_number() {
            return Math.log10(14);
        } document.write(value_of_base_e_logarithms_of_any_number());
      
    </script>

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    Output:

    1.146128035678238


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