Python math.log10() Method

1. Syntax
2. Example 1: Base-10 Logarithm of a Number
3. Example 2: If Input Is Not a Number
4. Example 3: If Input Less Than or Equal to 0
5. Example 4: If Input Is Infinity
6. Example 5: If Input Is NaN

The Python programming language offers a library, math, that contains implementation for various mathematical operations such as trigonometric functions and logarithmic functions.

Logarithm refers to the inverse function of exponentiation. Simply put, the logarithm of a number a is the exponent or number (x) to which another number, the base b, should be raised to make that number a.

In this article, we will discuss a method, log10(), available in the math module that computes the logarithm of a number with base 10.

Syntax

math.log10(x)

Parameters

Return

The log10() method returns the logarithm to the base of 10 for a number. It is equivalent to math.log(x, 10) and, in some cases, more accurate than it.

Example 1: Base-10 Logarithm of a Number

import math

print(math.log10(0.000001))
print(math.log10(1))
print(math.log10(0.341))
print(math.log10(99999))
print(math.log10(2352.579))

Output:

-6.0
0.0
-0.4672456210075022
4.999995657033466
3.3715442160261846

The Python code above computes the base-10 logarithm value for 0.000001, 1, 0.341, 99999, and 2352.579. Note that these values are non-negative and non-zero.

For inputs in the range (0, 1), the base-10 logarithm returns negative results. On the flip side, the range [1, ∞) yields positive results.

Example 2: If Input Is Not a Number

import math

print(math.log10("this is a string"))

Output:

Traceback (most recent call last):
  File "main.py", line 3, in <module>
    print(math.log10("this is a string"))
TypeError: must be real number, not str

The Python code above takes a string as an input. Since the log10() method expects a numeric value such as an integer or a float, it raises a TypeError exception.

Example 3: If Input Less Than or Equal to 0

import math

print(math.log10(0))

Output:

Traceback (most recent call last):
  File "main.py", line 3, in <module>
    print(math.log10(0))
ValueError: math domain error

The Python code above takes 0 as input, and since 0 is out of the log10() method’s domain, it raises a ValueError exception.

import math

print(math.log10(-99.09))

Output:

Traceback (most recent call last):
  File "main.py", line 3, in <module>
    print(math.log10(-99.09))
ValueError: math domain error

The Python code above takes -99.09 as input which is less than 0. Such values are invalid for the log10() method because they lie outside its domain.

Hence, it raises a ValueError exception.

Example 4: If Input Is Infinity

import math

print(math.log10(math.inf))

Output:

inf

The logarithm of infinity to base 10 is infinity.

Example 5: If Input Is NaN

import math

print(math.log10(math.nan))

Output:

nan