Book Image

The Complete Edition - Software Engineering for Real-Time Systems

By : Jim Cooling
Book Image

The Complete Edition - Software Engineering for Real-Time Systems

By: Jim Cooling

Overview of this book

From air traffic control systems to network multimedia systems, real-time systems are everywhere. The correctness of the real-time system depends on the physical instant and the logical results of the computations. This book provides an elaborate introduction to software engineering for real-time systems, including a range of activities and methods required to produce a great real-time system. The book kicks off by describing real-time systems, their applications, and their impact on software design. You will learn the concepts of software and program design, as well as the different types of programming, software errors, and software life cycles, and how a multitasking structure benefits a system design. Moving ahead, you will learn why diagrams and diagramming plays a critical role in the software development process. You will practice documenting code-related work using Unified Modeling Language (UML), and analyze and test source code in both host and target systems to understand why performance is a key design-driver in applications. Next, you will develop a design strategy to overcome critical and fault-tolerant systems, and learn the importance of documentation in system design. By the end of this book, you will have sound knowledge and skills for developing real-time embedded systems.
Table of Contents (16 chapters)
Preface
15
Glossary of terms

12.3 Numerical Issues

12.3.1 Problems in Disguise

Do we really need to understand how mathematical operations are carried out within a computer? Well, consider the situations depicted in Figure 12.1:

Figure 12.14: Operations requiring numerical processing

In (a), we use the calculation (0 - X) to determine whether X has a negative value. The next example, (b), shows the output from a shaft angle sensor being fed to a control computer to provide data monitoring. In (c), a missile aimer measures the angle between a fixed reference point and a target aircraft in order to engage at the optimal launch angle. The final item, (d), is a simple mathematical statement in source code form.

If you are likely to work with these or similar applications, then you do need to know what happens during the number-crunching process. This is because there are disguised problems in all of these examples. For instance, in (a), the calculation may give a false result indicating...