UNIT 1 : INTRODUCTION

COMPUTATION

• The term Computation refers to the process of arriving at output from a given problem. 
• It should be logical and the process should follow a step by step approach to arrive at a meaningful output or result. 
• To achieve this, the basic computation model should be followed. 

STEPS IN PROBLEM SOLVING   

• The steps in problem solving are called as Program Development Life Cycle (PDLC).
• It is shown in the below diagram.

 

• Problem Definition

• Identify & define the problem
• It must be stated clearly, accurately & precisely
• It should not be ambiguous

• Problem Analysis 

• The following should be stated clearly 
• Input specification
• Output specification
• The processing steps required to convert given inputs to outputs.

• Designing A Problem

• Designing the solution for the problem 
• Obtained by using the program design tools 
• Algorithms - step by step procedure of solving a problem 
• Flowcharts - graphical representation of the algorithm. 
• The following ways are also followed 
• Top-down design approach 
• The problem is divided into sub-problems and further dividing them into smaller sub-problems until it is small enough to solve the problem individually. 
• Allows the programmer to build a solution in a step-wise manner 
• Bottom-up design 
• Modular design

• Coding

• Writing the instructions in a particular language to solve a problem 
• Data items, variables & constants are defined

• Testing A Program

• Testing is done to verify the quality of the program (completeness, correctness, reliability & maintainability)
• Testing can be done at the following levels
• Unit testing
• Program testing
• Verification testing
• Validation testing

• Maintaining A Program

• Modifications based on user requirements
• Periodic review of the programs & modifications based on user requirements
• Requires proper documentation
• Its a continuous activity