What is `inf` in Python?

When solving coding tests or similar tasks in Python, there are times when you need to assign a very large value to a variable meant to store the minimum value. In such cases, using inf ensures that any number compared to it will always be smaller.

min_val = float('inf')
print(min_val > 10000000000)  # True
print(min_val > -100)         # True

Similarly, for negative values, you can use -inf to set the smallest possible value.

max_val = float('-inf')
print(max_val < -10000000000) # True
print(max_val < 100)          # True

You don't have to use only float('inf'), you can also use math.inf. Both methods represent infinity and can be chosen based on your coding style or whether you're using the math module.

import math

min_val = math.inf
print(min_val > 10000000000)  # True

The principle of inf is based on the IEEE 754 standard. Python's float follows this standard for floating-point numbers. According to this standard, certain bit patterns are designated to represent special values such as "infinity."

When you use float('inf') or math.inf, Python stores this as a floating-point value that it interprets as infinity. These values are designed to always be greater than any other number (or smaller in the case of -inf).