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The Python math.isinf() method is used to determine whether a given number is positive or negative infinity. It returns "True" if the number is positive or negative infinity, and "False" otherwise.

For example, if you have a floating-point number "x = float('inf')", which represents positive infinity, the math.isinf(x) method will return "True", indicating that ∞ is infinite. Similarly, if you have a floating-point number "y = float('-inf')", which represents negative infinity, the math.isinf(y) method will also return "True", indicating that -∞ is infinite.

Syntax

Following is the basic syntax of the Python math.isinf() method −

math.isinf(x)

Parameters

This method accepts a numeric value as a parameter representing the floating-point number to be checked for infinity.

Return Value

The method returns a boolean value (True or False) indicating whether the given value "x" is positive or negative infinity.

Example 1

In the following example, we check if positive infinity is infinite using the math.isinf() method −

import math
result = math.isinf(float('inf'))
print("The result is:",result)       

Output

The output obtained is as follows −

The result is: True

Example 2

Here, we check if negative infinity is infinite using the math.isinf() method −

import math
result = math.isinf(float('-inf'))
print("The result is:",result)  

Output

Following is the output of the above code −

The result is: True

Example 3

Now, we are checking if the number "100" is infinite using the math.isinf() method −

import math
result = math.isinf(float(100))
print("The result is:",result)  

Output

We get the output as shown below −

The result is: False

Example 4

In this example, we are checking if NaN (Not a Number) is infinite using the math.isinf() method −

import math
result = math.isinf(float('nan'))
print("The result is:",result)  

Output

The result produced is as shown below −

The result is: False

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