Recursion

Definition

recursion n. See recursion.

Recursion in Mathematics

n! or fact(n) is defined as:

     fact(0) = 1  
     fact(n) = n*fact(n-1) , for  n > 0

the nth fibonacci number or fib(n) is defined as:

     fib(0) = 1
     fib(1) = 1
     fib(n) = fib(n-1) + fib(n-2) , for  n > 1 

Recursion in Programs

• Each time the function calls itself, it gets a new set of parameters and local variables.

• The parameters and local variables from a previous call to the recursive function will still be preserved until the function returns from the previous call.

factorial function in C

     int Factorial (int n)
     {
         if(n==0) 
	 {
             return (1);
         }
         else 
	 {
	     return (n * Factorial(n - 1)));
	 }
    }