Within software engineering, software is very rarely written by a single software engineer. Usually a team of engineers write a program; therefore a formal structural design approach is required. The approach is to take a complex task e.g. VAX vms and divide it into smaller simpler tasks e.g. print, dir ,set pass etc. As long as the interfacing between these programs is well defined i.e. variable used etc. all the modules can be coded at once, thus reducing time. It is usual to code the program as modules , functions  Very often a program consists of a series of function calls .Within software there are advanced  module design /development tools namely CASE and JSD/JSP , let us consider a simple approach to structure .  In order to help document these functions, it is usual to have an overall module diagram design; illustrating the input which has caused the function to operate and its output e.g. consider the password program

Secondly the next stage of design is an algorithm for each module consisting of a title block, detailing the author, amendment date, variable used, inputs, outputs required and function. Despite the increased time in documentation, considerable time is saved by using more than one programmer. All your assignments and exercises should now be constructed in a modular design approach with an associated module diagram and algorithms. Let us consider the matrix program in module format and its design.