Python language Recursive function

In this tutorial, we discuss Python language Recursive function.

When a function calls itself it is called as recursion. The python language allows creating the recursive function to perform a special task

The following example explains how to find the adding of the limited natural numbers using the recursive function

Example of recursive function

Calculate the sum of natural numbers using recursion

The following is an example of the recursive function to total a series of the integer numbers

Program 1

def sum_Num(num):
    if num == 0:
       return 0
    else:
       return num + sum_Num(num-1)
print("Sum of the first 100 numbers is",sum_Num(100))
print("Sum of first 500 numbers is",sum_Num(500))

When the above code executed, it produces the following results

Sum of the first 100 numbers is 5050
Sum of first 500 numbers is 125250

In the above example, to find the total of given numbers, when we passing the argument of the positive integer of this function, it will recursively call itself decreasing one by one until it becomes one from a given number.

Program 2

following example explain how to find the factorial of a number using a recursive function in python.

factorial of a number is the product of the all integer from one to until the given number

For example, the factorial of 5 is 1*2*3*4*5n=120

Find factorial using recursion

#This is a example for find factorial
#using recursive function in Pyton

def calc_fact(n):

    if n==1:
        return 1;
    else:
        return(n*calc_fact(n-1))

num= int(input("Enter the number for find factorial: "))
# take input from user for find factorial

print("The factorial of ",num," is", calc_fact(num))
#display factorial

When the above code executed, it produces the following results

Enter the number for find factorial: 5
The factorial of 5 is 120

In the above example, calc_fact() is a recursive function as it calls itself to find factorial.

Factorial of n is the product of all the integer from 1 to the factorial of n is 1*2*3*4……..*n-1*n.

In the above example, to find the factorial of a given number, when we pass the argument as the positive integer of this function, it will recursively call itself decreasing one by one until it becomes one from a given number

Advantages of recursion in Python

Easy to understand and code readability and reduce the line of the program.
A big and complex task easy to make using subprogram using recursion
very flexible and repeatedly functioning is easier with using nesting iteration

Disadvantages of recursion in Python

Tracing and debugging are very difficult
every recursive allocates separate memory location so requires extra memory and very slow

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