Algorithm

Algorithms

An algorithm is a precise specification of a sequence of instruction for solving a problem in a finite number of steps. The algorithm must be written in the human understandable form and each step or instruction must tell the reader what task is to be done clearly. It must be written independently of any programming language. Some of the characteristics of algorithm are mentioned below:

• Input: Every algorithm accepts an input or set of inputs and process them to get the result.
• Effectiveness: It must process the input in the correct manner for solving the problem.
• Finiteness: It must terminate after a finite number of steps.
• Robustness: Must be clearly written to understand and must have an unambiguous meaning.
• Simplicity: It must be as simple as possible.
• Correctness: It must produce the same output for same sets of input.
• Output: It must generate some sort of output.

Design of Algorithm

Algorithms are never designed to bolster a specific programming code. As we know that all programming languages share the basic code builds like loops (do, for, while), flow-control (if-else) and so forth. So, these normal constructs can be utilized to design an algorithm. We generally design algorithms in a number of steps. Algorithm designing is a procedure and is executed after the issue area is very much characterized i.e. we ought to know the issue area, for which we are designing an answer. An algorithm to add two numbers and display the result is given below:

step 1 − START ADD

step 2 − get values of a & b

step 3 − c ← a + b

step 4 − display c

step 5 – STOP

A problem can be solved in multiple ways, so we need to analyse the algorithms and select the best one for implementation.

Algorithm Validation

Algorithm validation is the process of measuring the effectiveness of an algorithm before it is coded to know that the algorithm is correct for every possible input. Providing a theoretical validation may not be possible in all cases. Alternatively, algorithm segments that have been validated or proved elsewhere can be used and the overall testing algorithm may be empirically validated for several test cases.

Analysis of Algorithm

Analysis of algorithms is a branch of computer science that studies the performance of algorithms, especially their run time and space requirements (Wikipedia, n.d.). The main objective of analysis of algorithm is to anticipate the performance of various algorithms in order to guide the design choices.

Algorithm Testing

For algorithm testing, we take an input, calculate by hand the expected output, and compare it to the output that the algorithm provides us. If the outputs are same by calculating manually and by using the algorithm, then we can confirm that the algorithm is true or efficient and that it can be used for further processing.

Sub-algorithm

A sub-algorithm is a complete and autonomously characterized algorithmic module in a data structure. It is called by the main algorithm and by some other sub-algorithm. It can get values from the calling algorithm. The syntax is:

name ( p1, p3, . . . . . . .. . . , pn )

{

body of sub - algorithm

}

where ‘name’ denotes the name of the sub-algorithm and ‘p1’, ‘p2’, ‘pn’ represents the parameters or arguments.

There are two sub-algorithms: function sub-algorithm and procedure sub-algorithm. The function sub-algorithm is called as an expression or as a variable and returns a single value through ‘return’ statements to the calling algorithm. The value returned by a sub-algorithm is used in an expression. The procedure sub-algorithms is called by the ‘call’ statement in algorithms and it can return more than one value through parameters.

References

(n.d.). Retrieved from Wikipedia: http://en.wikipedia.org/wiki/Analysis_of_algorithms.