Other than the fact that `math.inf`

and `-math.inf`

were introduced in Python 3.5, there are *no* differences between them, and `float('inf')`

and `float('-inf')`

. They both follow the IEEE 754 floating-point standard and are *equivalent* representations of positive and negative infinity, respectively. Therefore, they can be used interchangeably. In fact, when you check the *type* of these values, you'll find that they are all of the *same* type:

import math print(type(math.inf)) # <class 'float'> print(type(float('inf'))) # <class 'float'> print(type(-math.inf)) # <class 'float'> print(type(float('-inf'))) # <class 'float'>

These representations can be used *interchangeably* in mathematical calculations, comparisons, and other operations. For instance, consider the following, where the `math.isinf()`

function can be seen to be compatible with both `math.inf`

and `float('inf')`

(and their negative counterparts):

import math print(math.isinf(math.inf)) # True print(math.isinf(-math.inf)) # True print(math.isinf(float('inf'))) # True print(math.isinf(float('-inf'))) # True print(math.isinf(42)) # False

Similarly, you can *directly* compare the values against *either* `math.inf`

or `float('inf')`

(and their negative equivalents):

import math print(math.inf == float('inf')) # True print(-math.inf == -float('inf')) # True

In the examples above, you can see that the values are equivalent to each other. The decision to choose one over the other *typically* depends on personal preference or the specific coding context. However, the `math.inf`

form is *often* preferred for semantics, readability and clarity.

This post was published by Daniyal Hamid. Daniyal currently works as the Head of Engineering in Germany and has 20+ years of experience in software engineering, design and marketing. Please show your love and support by sharing this post.