Recursion software ltd

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The following companies represent a subset of customers using our products to develop mission critical applications for their end customers. Call us for a FREE download of SCADA-Aware Mobile quick contact send inquiry request call back contact us request a demo Welcome to Recursion Software Founded in , Recursion Software is a leader in distributed computing, mobile agents, middleware, and mobile device computing, with over 80 patents and applications.

Webtek Software 11th Jun, Virtual Dynamics Software 11th Jun, Tech Vedika Software 11th Jun, Autosar Interview Questions 21st Dec, Automobile Engineering 21st Dec, Related Articles. Bamboo Software Solutions. B2b Software Technologies. C S Software Enterprise Ltd. Inteq Software. New User? Your Country. This will go like that until the message reaches the shortest doll. The shortest doll who is the only one who knows the secret answer will pass the answer to the next taller doll found on her left , which will pass it to the next taller doll This is what recursion really does.

That's why when you write recursive code it's very important to decide about when recursion should terminate. Recursion n. The classic example is finding the factorial of a number, n!. So, 6! This basic definition would allow you to create a simple iterative solution:. However, examine the operation again.

By the same definition, 5! In turn, 5! By doing this, we reduce the problem to an operation performed on the result of all previous operations. This eventually reduces to a point, called a base case, where the result is known by definition. In our case, 0! In computing, we are often allowed to define algorithms in a very similar way, by having the method call itself and pass a smaller input, thus reducing the problem through many recursions to a base case:.

This can, in many languages, be further simplified using the ternary operator sometimes seen as an Iif function in languages that don't provide the operator as such :. The example I use is a problem I faced in real life.

You have a container such as a large backpack you intend to take on a trip and you want to know the total weight. You have in the container two or three loose items, and some other containers say, stuff sacks. The weight of the total container is obviously the weight of the empty container plus the weight of everything in it.

For the loose items, you can just weigh them, and for the stuff sacks you could just weigh them or you could say "well the weight of each stuffsack is the weight of the empty container plus the weight of everything in it". And then you keep going into containers into containers and so on until you get to a point where there are just loose items in a container. That's recursion. You may think that never happens in real life, but imagine trying to count, or add up the salaries of, people in a particular company or division, which has a mixture of people who just work for the company, people in divisions, then in the divisions there are departments and so on.

Or sales in a country that has regions, some of which have subregions, etc etc. These sorts of problems happen all the time in business. Recursion can be used to solve a lot of counting problems. How many handshakes take place? Suppose you have three people. After that you have to count just the handshakes between the other two people. We already did that just now, and it is 1. Suppose you have n people. In life as opposed to in a computer programme recursion rarely happens under our direct control, because it can be confusing to make happen.

Also, perception tends to be about the side effects, rather than being functionally pure, so if recursion is happening you might not notice it. Another place you can get recursion is in English and human language in general. You might not recognise it at first, but the way we can generate a sentence is recursive, because the rules allow us to embed one instance of a symbol in side another instance of the same symbol.

The act of understanding the full sentence involves understanding smaller sentences, which use the same set of mental trickery to be understood as the full sentence. To understand recursion from a programming perspective it's easiest to look at a problem that can be solved with recursion, and understand why it should be and what that means you need to do. You have your two numbers a and b. To find their gcd assuming neither is 0 you need to check if a is evenly divisible into b.

You should already be able to see that this is a recursive function, as you have the gcd function calling the gcd function. Just to hammer it home, here it is in c again, assuming 0 never gets passed in as a parameter :. In a programme, it is important to have a stopping condition, otherwise you function will recur forever, which will eventually cause a stack overflow!

The reason to use recursion here, rather than a while loop or some other iterative construct, is that as you read the code it tells you what it is doing and what will happen next, so it is easier to figure out if it is working correctly. Let them imagine that they have a comic collection and you're going to mix it all up into a big pile. Careful -- if they really have a collection, they may instantly kill you when you just mention the idea to do so.

The nice thing here is: When they are down to single issues, they have the full "stack frame" with the local piles visible before them on the ground. Give them multiple printouts of the manual and put one aside each pile level with a mark where you currently are on this level ie. That's what recursion basically is about: Performing the very same process, just on a finer detail level the more you go into it.

Recursion is a very concise way to express something that has to be repeated until something is reached. Consider a painter painting a wall, it's recursive because the action is "paint a strip from ceiling to floor than scoot over a little to the right and paint a strip from ceiling to floor than scoot over a little to the right and paint a strip from ceiling to floor than scoot over a little to the right and etc ".

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Learn more. In plain English, what is recursion? Ask Question. Asked 11 years, 1 month ago. Active 6 years, 9 months ago. Viewed k times. Improve this question.

More information is being shared on this subject at Resources for improving your comprehension of recursion? See also: programmers. Recursion is when a function can call itself. I can show examples, but you should be able to figure out how they work on your own. Before diving into recursion, make sure the students can properly trace through a program where you've purposely given variables at different scopes the same name to confuse them.

Show 3 more comments. Active Oldest Votes. To explain recursion , I use a combination of different explanation, usually to both try to: explain the concept, explain why it matters, explain how to get it. For starters, Wolfram Alpha defines it in more simple terms than Wikipedia : An expression such that each term is generated by repeating a particular mathematical operation.

Maths If your student or the person you explain too, from now on I'll say student has at least some mathematical background, they've obviously already encountered recursion by studying series and their notion of recursivity and their recurrence relation. A very good way to start is then to demonstrate with a series and tell that it's quite simply what recursion is about: a mathematical function Coding Examples For the rest, it's actually a detailed version of what I presented in the Addendum of my answer for the question you pointed to regarding pointers bad pun.

I usually resort to a few repetitive and simple programming problems until they get it: the factorial operation, an alphabet printer, a reversed alphabet printer, the exponentation operation.

Factorial Factorial is a very simple math concept to understand, and the implementation is very close to its mathematical representation. Alphabets The alphabet version is interesting to teach them to think about the ordering of their recursive statements.

Exponentiation The exponentiation problem is slightly more difficult at this stage of learning. Its simple form: can be expressed like this by recurrence: Harder Once these simple problems have been shown AND re-implemented in tutorials, you can give slightly more difficult but very classic exercises: The Fibonacci numbers, The Greatest Common Divisor , The 8-Queens problem, The Towers of Hanoi game, And if you have a graphical environment or can provide code stubs for it or for a terminal output or they can manage that already , things like: Koch's Snow Flake Fractal , Sierpinski's Triangle.

And for for practical examples, consider writing: a tree traversal algorithm, a simple mathematical expression parser, a minesweeper game. Helpers A Reference Some reading never hurts. The Stack-as-Drawers Diagram Indenting a printed result or the level's output helps as well, as it gives another visual representation of what your program is doing, opening and closing stack contexts like drawers, or folders in a file system explorer.

Pitfalls and Further Learning Some issues that people usually struggle with and for which you need to know answers. Why, oh God Why??? This code is contributed by pratham Diagram of factorial Recursion function for user input 5. Previous Practice Questions for Recursion Set 7. Next Practice Questions for Recursion Set 1.

Recommended Articles. Article Contributed By :. Easy Normal Medium Hard Expert. Writing code in comment? Please use ide. Load Comments. What's New. Most popular in Algorithms. Most visited in Recursion. Given an array A[] and a number x, check for pair in A[] with sum as x aka Two Sum Write a program to print all permutations of a given string Josephus problem Set 1 A O n Solution Write a program to reverse digits of a number Program for Sum of the digits of a given number.

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