D.4.01 Define the term Recursion.
RECURSION
Recursion is the concept of well-defined self-reference.
It is the determination of a succession of elements (as numbers or functions) by operation on one or more preceding elements according to a rule or formula involving a finite number of steps
It is the process a procedure goes through when one of the steps of the procedure involves invoking the procedure itself.
A procedure that goes through recursion is said to be 'recursive'.
To understand recursion, one must recognize the distinction between a procedure and the running of a procedure. A procedure is a set of steps based on a set of rules. The running of a procedure involves actually following the rules and performing the steps. An analogy: a procedure is like a written recipe; running a procedure is like actually preparing the meal.
RECURSIVE SOLUTION
A recursive solution describes a procedure for a particular task in terms of applying the same procedure to a similar but smaller task.
A recursive solution isolates simple situations, called base cases (or stopping cases) when a computation is obvious and recursion is not required.
REFERENCES
"Recursion | Definition of Recursion by Merriam-Webster." 2005. 24 Oct. 2016 <http://www.merriam-webster.com/dictionary/recursion>
"Recursion - Wikipedia." 2011. 24 Oct. 2016 <https://en.wikipedia.org/wiki/Recursion>