ABSTRACT
This chapter outlines a few typical ways of discovering the weak spots in a microcomputer's armour, and discusses how the correct analysis of a problem can help to improve speed and accuracy. Subroutines usually contain some set of statements which have to be used many times during a program and avoid the need to write that set explicitly many times in the program. Subroutines would be needed on grounds of economy even if computers were of infinite memory. If the computer does not have natural BASIC instructions for operations such as adding and multiplying complex numbers and matrices then special subroutines to do the job will be required. Once written they can be used over and over again in many programs. The program can be used to illustrate how non-commutativity of addition can occur on a computer.
