In Python, you can represent "infinity" (i.e. an infinite number) in the following two ways:
 Using
math.inf
ormath.inf
(Python 3.5+);  Using
float('inf')
orfloat('inf')
.
Please note that both these representations follow the IEEE 754 floatingpoint standard, are equivalent, and can be used interchangeably.
Using math.inf
or math.inf
Starting with Python 3.5, you can use math.inf
and math.inf
to represent positive and negative infinity respectively:

Positive Infinity:
The value
math.inf
(i.e. positive infinity) is always greater than any other number:# Python 3.5+ import math print(math.inf > 100) # True print(math.inf > 0) # True print(math.inf > 100) # True

Negative Infinity:
The value
math.inf
(i.e. negative infinity) is always less than any other number:# Python 3.5+ import math print(math.inf < 100) # True print(math.inf < 0) # True print(math.inf < 100) # True
You can use positive and negative infinity as you would any other value in Python. For example:
# Python 3.5+ import math # assigning infinity to a variable inf = math.inf print("Infinity:", inf) # "Infinity: inf"
# Python 3.5+ import math # function that returns infinity def get_infinity(): return math.inf result = get_infinity() print("Returned Infinity:", result) # "Returned Infinity: inf"
You can check if a value is infinite by using the math.isinf()
function:
# Python 3.5+ import math # function that takes infinity as an argument def is_inf(value): # check if infinity using `math.isinf()` return math.isinf(value) print(is_inf(math.inf)) # True print(is_inf(math.inf)) # True print(is_inf(float('inf'))) # True print(is_inf(float('inf'))) # True print(is_inf(42)) # False print(is_inf(42)) # False
Using float('inf')
or float('inf')
float('inf')
and float('inf')
can be used to represent positive and negative infinity respectively:

Positive Infinity:
The value
float('inf')
(i.e. positive infinity) is always greater than any other number:print(float('inf') > 100) # True print(float('inf') > 0) # True print(float('inf') > 100) # True

Negative Infinity:
The value
float('inf')
(i.e. negative infinity) is always less than any other number:print(float('inf') < 100) # True print(float('inf') < 0) # True print(float('inf') < 100) # True
You can use positive and negative infinity as you would any other value in Python. For example:
# assigning infinity to a variable inf = float('inf') print("Infinity:", inf) # "Infinity: inf"
# function that returns infinity def get_infinity(): return float('inf') result = get_infinity() print("Returned Infinity:", result) # "Returned Infinity: inf"
You can check if a value is infinite by directly comparing the value against float('inf')
or float('inf')
:
import math # function that takes infinity as an argument def is_inf(value): # directly comparing value against infinity return value == float('inf') or value == float('inf') print(is_inf(math.inf)) # True print(is_inf(math.inf)) # True print(is_inf(float('inf'))) # True print(is_inf(float('inf'))) # True print(is_inf(42)) # False print(is_inf(42)) # False
This post was published (and was last revised ) 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.