Python math function | sqrt()

Difficulty Level : Basic
Last Updated : 11 Jan, 2018

sqrt() function is an inbuilt function in Python programming language that returns the square root of any number.

Syntax:
math.sqrt(x)

Parameter: 
x is any number such that x>=0 

Returns:
It returns the square root of the number 
passed in the parameter.

# Python3 program to demonstrate the 
# sqrt() method 
  
# import the math module 
import math 
  
# print the square root of  0 
print(math.sqrt(0)) 
  
# print the square root of 4
print(math.sqrt(4)) 
  
# print the square root of 3.5
print(math.sqrt(3.5)) 

Output:

0.0
2.0
1.8708286933869707

Error: When x<0 it does not executes due to a runtime error.

# Python3 program to demonstrate the error in 
# sqrt() method 
  
# import the math module 
import math 
  
# print the error when x<0 
print(math.sqrt(-1)) 

Output:

Traceback (most recent call last):
  File "/home/67438f8df14f0e41df1b55c6c21499ef.py", line 8, in 
    print(math.sqrt(-1)) 
ValueError: math domain error

Practical Application : Given a number, check if its prime or not.
Approach: Run a loop from 2 to sqrt(n) and check if any number in range (2-sqrt(n)) divides n.

# Python program for practical application of sqrt() function
  
# import math module
import math
  
# function to check if prime or not 
def check(n):
    if n == 1:
        return False
          
        # from 1 to sqrt(n) 
    for x in range(2, (int)(math.sqrt(n))+1):
        if n % x == 0:
            return False 
    return True
  
# driver code
n = 23
if check(n):
    print("prime") 
else:
    print("not prime")

Output:

prime

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