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.

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Syntax

The syntax to call log() function is

math.log(x, base)

where

Parameter	Required	Description
x	Yes	A numeric value. The value must be greater than 0.
base	No	A 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.

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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

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Summary

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