# How to Represent "Infinity" in Python?

In Python, you can represent "infinity" (i.e. an infinite number) in the following two ways:

Please note that both these representations follow the IEEE 754 floating-point 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.