This is a very compact introductory textbook in Numerical Analysis. Its main goal is to give to the reader an idea of what Numerical Analysis is by providing several elementary but significant examples in the main chapters of the field. I wrote it so that I could use it in the MATH 164 course at Howard University, since I could not find an optimal textbook for that course. The main goals I had in mind while writing the book were:
focusing, for each topic covered, on numerical algorithms and showing simple concrete implementations thereof, and so limiting the theory to a bare minimum -- if you are looking for a book about "theoretical numerical analysis", this is not it;
having a book easily accessible from any kind of device and that allows students to edit and run code from within the book itself.
I am very grateful to the developers of PreTeXt and SageMathCell for making this possible. The book is structured as follows. The first sections of each chapter present the chapter's content and include "alive code", namely code that runs in the page itself and whose output, including plots, is shown in the page after pressing the corresponding "Evaluate" button. The code can be (and is meant to be!) freely edited by the reader to see what happens after small modifications of the code -- in the author's opinion, the best way to learn programming is to mess with the code and see what happens at every change, kind of learning by "inverse scattering". The last section of each chapter is dedicated to a recap of the new Python language syntax used in that chapter's code. Notice that, as a rule, in this book we introduce and use only the parts of the language we need -- a quite small set but more than enough to accomplish our numerical goals. The reference source for learning Python is Python's Wiki but, in the author's intentions, these recaps help the readers with low or none familiarity with the language to find the essential information needed to understand that section's code and links for those that want to know more. The union of all recaps sections should enable the reader to write his/her own code to solve simple numerical problems by his/her own. Finally, we provide some exercises relative to the chapter's content and a list of references and suggested readings, most of which at an elementary level.
Roberto De Leo Washington, November 2023
