"Version: 20251101"--Title page verso.Includes bibliographical references.part I. Mathematical background. 1. Vectors and tensors -- 1.1. Introduction -- 1.2. Vector calculus -- 1.3. Generalization of matrices into tensors -- 1.4. Geometric algebra -- 1.5. Group theory2. Differential equations and the Lagrangian formalism -- 2.1. Differential equations -- 2.2. Differential equations with severa…