The term algorithm originally referred to any computation performed via a set of rules applied to numbers written in decimal form. The word is derived from the phonetic pronunciation of the last name of Abu Ja'far Mohammed ibn Musa al-Khowarizmi, who was an Arabic mathematician who invented a set of rules for performing the four basic arithmetic operations (addition, subtraction, multiplication and division) on decimal numbers.
An algorithm is a representation of a solution to a problem. If a problem can be defined as a difference between a desired situation and the current situation in which one is, then a problem solution is a procedure, or method, for transforming the current situation to the desired one. We solve many such trivial problems every day without even thinking about it, for example making breakfast, travelling to the workplace etc. But the solution to such problems requires little intellectual effort and is relatively unimportant. However, the solution of a more interesting problem of more importance usually involves stating the problem in an understandable form and communicating the solution to others. In the case where a computer is part of the means of solving the problem, a procedure, explicitly stating the steps leading to the solution, must be transmitted to the computer. This concept of problem solution and communication makes the study of algorithms important to computer science.
Throughout history, man has thought of ever more elegant ways of reducing the amount of labour needed to do things. A computer has immense potential for saving time/energy, as most (computational) tasks that are repetitive or can be generalized can be done by a computer. For a computer to perform a desired task, a method for carrying out some sequence of events, resulting in accomplishing the task, must somehow be described to the computer. The algorithm can be described on many levels because the algorithm is just the procedure of steps to take and get the result. The language used to describe an algorithm to other people will be quite different from that which is used by the computer, however the actual algorithm will in essence be the same.
Algorithm can be defined as: “A sequence of activities to be processed for getting desired output from a given input.”
Webopedia defines an algorithm as: “A formula or set of steps for solving a particular problem. To be an algorithm, a set of rules must be unambiguous and have a clear stopping point.”
There may be more than one way to solve a problem, so there may be more than one algorithm for a problem. Now, if we take definition of algorithm as: “A sequence of activities to be processed for getting desired output from a given input.” Then we can say that:
1. Getting specified output is essential after algorithm is executed.
2. One will get output only if algorithm stops after finite time.
3. Activities in an algorithm to be clearly defined in other words for it to be unambiguous.
Alternatively, we can define an algorithm as a set or list of instructions for carrying out some process step by step. A recipe in a cookbook is an excellent example of an algorithm. The recipe includes the requirements for the cooking or ingredients and the method of cooking them until you end up with a nice cooked dish.
Example of a recipe to make a cake.
"4 extra large eggs, beaten
1&1/2 C. stock
1/2 teaspoon salt
1 scallion, minced
1 C. small shrimp or lobster flakes
1 t. soy sauce
1 Tablespoon oil
1. Mix all the ingredients, except the oil, in a deep bowl.
2. Put 1water in wide pot, then place deep bowl of batter inside.
3. Cover pot tightly and steam 15 min.
4. Heat oil very hot and pour over custard.
5. Steam 5 more min.
