Part IV of the book explains what is inside the code and how it works. This knowledge will make it possible to use the optimization code with more confidence, and more reliably. It will also help you know what to do when things do not work. The material presented will also be great preparation for further studies in optimization. With this more advanced knowledge, it will be possible to understand such things as the code error messages. The material examined in this part of the book will reinforce and advance the knowledge of optimization that was previously learned.

Metaphorically, the material up to this point taught us how to drive the design from a bad state to an optimal state. We did so without understanding how the car we are driving works, how to fix it, design it, or actually build it. However, we have sufficient practical knowledge to drive from a bad to a good design. The following material will teach us how the car works, how to fix it, how to make it perform very well, and even prepare us venture into the advanced world of designing cars (if that is our interest). That is, building optimization codes and algorithms. Interestingly, most of us want to use the power of optimization, without having to become expert in the intricate details of the inner-workings of the optimization code. This book provides the breadth of presentation to suit these diverse objectives. More advanced topics will be presented beyond Part IV.