Python Program to Find the Square Root

In this program, you’ll learn to find the square root of a number using exponent operator and cmath module.

To understand this example, you should have the knowledge of the following Python programming topics:

• Python Input, Output and Import
• Python Data Types
• Python Operators

1. Example: For positive numbers

# Python Program to calculate the square root

# Note: change this value for a different result
num = 8 

# To take the input from the user
#num = float(input('Enter a number: '))

num_sqrt = num ** 0.5
print('The square root of %0.3f is %0.3f'%(num ,num_sqrt))

Output

The square root of 8.000 is 2.828

In this program, we store the number in num and find the square root using the ** exponent operator. This program works for all positive real numbers. But for negative or complex numbers, it can be done as follows.

2. Source code: For real or complex numbers

# Find square root of real or complex numbers
# Importing the complex math module
import cmath

num = 1+2j

# To take input from the user
#num = eval(input('Enter a number: '))

num_sqrt = cmath.sqrt(num)
print('The square root of {0} is {1:0.3f}+{2:0.3f}j'.format(num ,num_sqrt.real,num_sqrt.imag))

Output

The square root of (1+2j) is 1.272+0.786j

In this program, we use the sqrt() function in the cmath (complex math) module.

Note: If we want to take complex number as input directly, like 3+4j, we have to use the eval() function instead of float().

The eval() method can be used to convert complex numbers as input to the complex objects in Python. To learn more, visit Python eval() function.

Also, notice the way in which the output is formatted. To learn more, visit string formatting in Python.