This book evolved from lecture notes developed over several years of teaching numerical methods at the University of Aarhus. The book contains short descriptions of some of the most common numerical methods together with illustrational implementations of the discussed algorithms mostly in the C programming language. The implementations are solely for educational purposes, they are not thoroughly tested and are not tuned in any way other than to fit nicely on a single page of the book; some simple optimizations were often sacrificed to conciseness. For serious calculations one should use the GNU Scientific Library.
The content of the book is free as in freedom. You are permitted to copy and redistribute the book in original or modified form either gratis or for a fee. However, you must attribute the original author(s) and pass the same freedom to all recipients of your copies. See the GPL and CC-BY-SA licenses for more details.