Python - math.log() method example

The math.log() method returns the natural logarithm (base e) of a number. 

import math

print(math.log(1))      # 0
print(math.log(7))      # 1.9459101490553132
print(math.log(10))     # 2.3025850929940460
print(math.log(100))    # 4.6051701859880920
print(math.log(1000))   # 6.9077552789821370

print(math.e)  # 2.718281828459045

# Logarithm with custom base is placed in the below example.

The math.log() method is presented on the following chart:

1. Documentation

math.log(x, newBase)

2. Logarithm with custom base example

This example shows a logarithmic function calculation with its own base.

import math


def calculate_logarithm(log_base, x):
    a = math.log(x)
    b = math.log(log_base)
    return a / b


# Logarithm with custom base:
#                          base     x              y
print(calculate_logarithm( 2,       2       ) )  # 1.0
print(calculate_logarithm( 2,       4       ) )  # 2.0
print(calculate_logarithm( math.e,  math.e  ) )  # 1.0
print(calculate_logarithm( 3,       9       ) )  # 2.0
print(calculate_logarithm( 3,       81      ) )  # 4.0
print(calculate_logarithm( 10,      10      ) )  # 1.0

References

1. Natural logarithm - Wikipedia