Python math.log() – Natural Logarithm

Python math.log()

math.log(x) function returns the natural logarithm of x.

We may also specify an optional base value to the log() function for calculating logarithm of x.

Syntax

The syntax to call log() function is

math.log(x, base)

where

ParameterRequiredDescription
xYesA numeric value. The value must be greater than 0.
baseNoA numeric value. The base value for logarithm calculation. The default value is e.

If x is an invalid value, such as a negative value, then log() raises ValueError.

Examples

In the following program, we find the natural logarithm of 2, using log() function of math module.

Python Program

import math

x = 2
result = math.log(x)
print('log(x) :', result)

Output

log(x) : 0.6931471805599453

Natural logarithm of a negative number.

Python Program

import math

x = -2
result = math.log(x)
print('log(x) :', result)

Output

ValueError: math domain error

Natural logarithm of infinity.

Python Program

import math

x = math.inf
result = math.log(x)
print('log(x) :', result)

Output

log(x) : inf

Logarithm of 1024 to base 4.

Python Program

import math

x = 1024
base = 4
result = math.log(x, base)
print('log(x) :', result)

Output

log(x) : 5.0

Summary

In this Python Examples tutorial, we learned the syntax of, and examples for math.log() function.