Recursion means "defining a problem in terms of itself". This can be a very powerful tool in writing algorithms. Recursion comes directly from Mathematics, where there are many examples of expressions written in terms of themselves.

Recursion is the process of defining a problem or the solution to a problem in terms of a simpler version of itself. Here the solution to finding your way home is two steps three steps. First, we don't go home if we are already home. Secondly, we do a very simple action that makes our situation simpler to solve.

Finally, we redo the entire algorithm. The above example is called tail recursion. This is where the very last statement is calling the recursive algorithm. Tail recursion can directly be translated into loops. Another example of recursion would be finding the maximum value in a list of numbers.

The maximum value in a list is either the first number or the biggest of the remaining numbers. Here is how we would write the pseudocode of the algorithm:.

The "work toward base case" is where we make the problem simpler e. The recursive call, is where we use the same algorithm to solve a simpler version of the problem. The base case is the solution to the "simplest" possible problem For example, the base case in the problem 'find the largest number in a list' would be if the list had only one number Adding three numbers is equivalent to adding the first two numbers, and then adding these two numbers again.

Note, in Matlab, a function can be called without all the arguments. The nargin function tells the computer how many values were specified. This reduces the number of parameters nargin sent in to the function from 3 to 2, and 2 is the base case!

In a recursive algorithm, the computer "remembers" every previous state of the problem. This information is "held" by the computer on the "activation stack" i. Consider a rectangle grid of rooms, where each room may or may not have doors on the North, South, East, and West sides. How do you find your way out of a maze?

**Calculate Power Of a Number Using Recursion in C++**

Here is one possible "algorithm" for finding the answer:. The "trick" here is of course, how do we know if the door leads to a room that leads to the exit?

The answer is we don't but we can let the computer figure it out for us. What is the recursive part about the above algorithm?

Its the "door leads out of the maze".The figure below shows how recursion works by calling itself over and over again.

### C Program to Calculate Power of a Number

The function name is sum which is a user-defined function, its return type is integer. This function takes only one argument as the input which is also of the type integer. So if you want to calculate from one to three you simply enter three.

So you can see the sum is called inside the sum function itself. So this is a recursive call that is inside the sum function and calling again the sum function with a new argument which is one less than what the number. Then I am saying enter number till which you want the sum of natural numbers to be calculated. Then I take the input from the user and then I created one more integer variable int total. So in the end, I say the sum is and the number n which entered by the user and finally, I printed out the total.

Inside the main function, I started off by defining a variable a of the type integer. The function fact is a user-defined function, its return type is long int and this function takes only one argument as the input which is of the type integer.

As you can see, inside the function we have only a few lines of code which is very simply. We have an if condition which checks if the n is equal to 0, if this is true then the control will return 1 else the function will return the factorial. Table of Contents. Recommended For You. Leave a Reply Cancel reply. Iteration repeatedly executes code this can be less expensive in both processor time and memory space.The power of a number base exponent is the base multiplied to itself exponent times.

Here we will solve this problem using recursion. We will first take base and exponent as input from user and pass it to a recursive functionwhich will return the value of base raised to the power of exponent base exponent.

Below program first takes base and exponent as input from user using scanf function and stores it in integer variables. It uses a user defined function getPower, that takes base and exponent as input parameters and returns the value of base exponent.

To find the power of a number, we can use Divide and Conquer approach. A divide and conquer algorithm solves a problem in three steps. It divides a problem into two or more sub problems. Such that each sub-problem is same as the original problem but for smaller data set. It solve each sub-problem recursively and stores the solution of each sub-problem If required. It combines the solutions of sub-problem to get the overall solution of original problem.

Below program contains a user defined function getPower, that takes base and exponent as input parameters and returns the value of base exponent. Function getPower implements the divide and conquer algorithm mentioned above to calculate the power of a number.

Toggle navigation Home. Write a C program to find power of a number a b using recursion. Let getPower int A, int n is a function which returns A n. Newer Post Older Post Home. C program to calculate power of a number. C program for palindrome check using recursion.

C program to reverse a number using recursion. C program to find factorial of a number using recursion. C program to reverse a number. C program to reverse a string using recursion. C program to reverse an array using recursion.

C program to find sum of digits of a number using recursion. List of all C Programs.Fibonacci series are the numbers in the following integer sequence 0, 1, 1, 2, 3, 5, 8, 13, 21, 34, 55, In mathematical terms, the Nth term of Fibonacci numbers is defined by the recurrence relation:.

Below program uses recursion to calculate Nth fibonacci number.

Drupal highslide moduleTo calculate Nth fibonacci number it first calculate N-1 th and N-2 th fibonacci number and then add both to get Nth fibonacci number. In below program, we first takes the number of terms of fibonacci series as input from user using scanf function. We are using a user defined recursive function named 'fibonacci' which takes an integer N as input and returns the N th fibonacci number using recursion as discussed above.

The recursion will terminate when number of terms are In line number 17, we are calling this function inside a for loop to get the N th term of series. Recursive program to print fibonacci series is not so efficient because it does lots of repeated work by recalculating lower terms again and again. Now, while calculating fibonacci 4 it will again calculate fibonacci 3 which we already calculated while calculating fibonacci 5.

We can solve this recalculation problem by memorizing the already calculated terms in an array. In the below program, we are using an integer array named 'fibonacciArray' to store the already calculated terms of fibonacci series N th term of fibonacci series is stored at fibonacciArray[N-1]. To calculate the N th term we add the last two fibinacci elements N-1 and N-2 th element stored in array. Finally we store the N th term also in array so that we can use it to calculate next fibonacci elements.

Toggle navigation Home. Write a C program to print fibonacci series using recursion. Click here for fibonacci series program using memorization. Newer Post Older Post Home. C Program to print fibonacci series.

C program for palindrome check using recursion. C program to find power of a number using recursion.

V the complete series downloadC program to find factorial of a number using recursion. C program to reverse a number. C program to reverse a string using recursion.

C program to reverse an array using recursion. C program to insert an element in an array. List of all C Programs.By using our site, you acknowledge that you have read and understand our Cookie PolicyPrivacy Policyand our Terms of Service. The dark mode beta is finally here.

Change your preferences any time. Stack Overflow for Teams is a private, secure spot for you and your coworkers to find and share information. I'm writing a recursion function to find the power of a number and it seems to be compiling but doesn't output anything. Your k is getting weird values because you will keep computing until you run out of memory basically, you will create many stack frames with k going to "-infinity" hypothetically.

That said, it is theoretically possible for the compiler to give you a warning that it will never terminate - in this particular scenario. However, it is naturally impossible to solve this in general look up the Halting problem.

## Find power of a number using recursion using c program

You don't need the else-if condition:. The big difference between this piece of code and the other example is that my version could get optimized for tail recursive calls. It means that when you call stepemi recursively, it doesn't have to keep anything in memory. As you can see, it could replace the variable in the current stack frame without having to create a new one.

## C program to find sum of digits using recursion

No variable as to remain in memory to compute the next recursion. If you can have optimized tail recursive calls, it also means that the function will used a fixed amount of memory. It will never need more than 3 ints. On the other hand, the code you wrote at first creates a tree of stackframe waiting to return. Each recursion will add up to the next one. Well, just to post an answer according to my comment seems I missed adding a comment and not a response :-D.

I think, mainly, you have two errors: you're checking n instead of k and you're returning 1 when power is 1, instead of returning n. I think that stepem function should look like:. Learn more. Recursion function to find power of number Ask Question.

2020 democratic primary scheduleAsked 6 years, 5 months ago. Active 2 years, 11 months ago. Viewed 18k times. Well the truth is that your n is never changing. It probably is doing infinite recursion until your stacks get filled.

Isn't that a infinite loop? I want to multiply the number n for k times. I think that you want to check k and not nam I wrong?

Active Oldest Votes. You should be checking the exponent k, not the number itself which never changes. ScarletAmaranth ScarletAmaranth 4, 2 2 gold badges 19 19 silver badges 31 31 bronze badges. If the function is tail recursive, it might be able to recurse idefinitely without using more memory than the function really need. Yeah, I added my tail call optimizable version.

Yes, there is even difference in semantic implications should such optimization be preset, but yes, meh.By using our site, you acknowledge that you have read and understand our Cookie PolicyPrivacy Policyand our Terms of Service.

The dark mode beta is finally here. Change your preferences any time. Stack Overflow for Teams is a private, secure spot for you and your coworkers to find and share information. I have to write a power method in Java. It receives two ints and it doesn't matter if they are positive or negative numbers.

It should have complexity of O logN. It also must use recursion. My current code gets two numbers but the result I keep outputting is zero, and I can't figure out why. The usual way people think of recursion is to try to find a solution for n-1, and work from there. However, the complexity of this is O n. There is one multiplication in every recursion step, and there are n steps. So It's O n.

### C program to find the power of a number using function

In order to make this O log nwe need every step to be applied to a fraction of n rather than just n But what happens if n is odd?

But we are talking about integer powers here. Handling fractions is a whole different thing. This actually gives us the right results for a positive n, that is.

But in fact, the complexity here is, again, O n rather than O log n. Because we're calculating the powers twice.Given two integers x and n, write a function to compute x n. Time Complexity of optimized solution: O logn Let us extend the pow function to work for negative y and float x. If you like GeeksforGeeks and would like to contribute, you can also write an article using contribute.

See your article appearing on the GeeksforGeeks main page and help other Geeks. Please write comments if you find anything incorrect, or you want to share more information about the topic discussed above. Writing code in comment?

Please use ide.

Pwc partsWrite a program to calculate pow x,n Median of two sorted arrays of same size Median of two sorted arrays of different sizes Minimum window size containing atleast P primes in every window of given range Median of an unsorted array using Quick Select Algorithm Sorting Algorithm Visualization : Merge Sort Place the prisoners into cells to maximize the minimum difference between any two Count of smaller elements on right side of each element in an Array using Merge sort Smallest subarray with GCD as 1 Segment Tree Expected number of moves to reach the end of a board Matrix Exponentiation Frequency of an integer in the given array using Divide and Conquer Minimum K such that sum of array elements after division by K does not exceed S Find the count of distinct numbers in a range Find N in the given matrix that follows a pattern Floyd-Rivest Algorithm.

Python3 program to calculate pow x,n. This code is contributed by Smitha Dinesh Semwal. Write power x, y. Python3 code for extended version. Load Comments.

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