Recursive functions in Python

In this lesson, you will learn about recursive functions in python and how to use them in programs.

Recursive functions in Python

We can define a function to call the other functions when necessary in python. When a defined function calls itself directly or indirectly, it is called a recursive function. Using the recursion function you can loop through data to reach a result.

While writing a recursive it is very easy for a user to slip into writing a function that never terminates, or one that uses excess amounts of memory or processor power. But is a very efficient way of complex programming.

Sample program using a recursive function in python

Input:

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def simple_recursion(x):
      if(x>0):
          return_value = x+simple_recursion(x-1)
          print(return_value)
      else:
          return_value = 0
      return return_value
print("nnRecursion function")
simple_recursion(3)

Output:

Recursion function
1
3
6

Another common example of using recursive function is the Fibonacci series

Input

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def fibonacci_series(n):
   if n <= 1:
       return n
   else:
       return(fibonacci_series(n-1) + fibonacci_series(n-2))
n_terms = 7
if n_terms <= 0:
   print("Fibonacci series cannot be printed")
else:
   print("Fibonacci series using recursive function:")
   for i in range(n_terms):
       print(fibonacci_series(i))

Output:

Fibonacci series using recursive function:
0
1
1
2
3
5
8