This book serves as an accessible and comprehensive introduction to GNU Octave, a high-level programming environment widely used for numerical computing. It guides readers through essential concepts and core functionalities, from basic vector and matrix operations to more advanced topics like creating customized toolboxes and integrating with C code. With practical examples and exercises, this guide enables users to harness Octave effectively for diverse scientific applications. What this Book will help me do Understand and utilize GNU Octave's syntax and core concepts. Perform data analysis operations on vectors and matrices efficiently. Write and debug Octave scripts to automate computational tasks. Create and implement customized functions and an Octave toolbox. Optimize and integrate Octave code with external libraries for more challenging computations. Author(s) Jesper Schmidt Hansen is an experienced educator and practitioner in numerical methods and computational tools. With a strong background in applying software to solve real-world scientific problems, Hansen brings practical insights to this guide. His clear teaching style ensures concepts are accessible and applicable, making complex topics approachable for beginners. Who is it for? This book is ideal for students, engineers, scientists, and professionals interested in learning GNU Octave for scientific computing. Beginners with basic mathematics knowledge will find the content approachable, while programmers seeking an alternative tool for numerical tasks can benefit too. Anyone eager to handle data processing with Octave will find this a helpful resource.