Python math.isnan() Function

Mathematics

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The math.isnan() function is used to determine whether or not a given value is Not a Number (NaN).

math.isnan(x)

Where, x is the value which we want to check whether it is Not a Number.

The return value of this function will be either True or False, depending on whether or not the given argument is a NaN.

What do we mean by 'Not a Number'?

Not a Number (NaN) is a special value used to represent any computation result which is undefined or meaningless. It is also known as an undefined number. This value can be returned when the result of a mathematical operation is undefined.For example

Division by zero, such as 1/0.
Calculating the square root of a negative number
Attempting to get logarithm of a negative number.

In Python, NaN is represented as float('nan')

import math

print(math.isnan(float('nan')))
print(math.isnan(float('-nan')))
print(math.isnan(math.nan))
print(math.isnan(-math.nan))

import math

print(math.isnan(0))
print(math.isnan(10000))
print(math.isnan(-0.111))
print(math.isnan(math.pi))
print(math.isnan(math.inf))
print(math.isnan(math.e))