Appendix A On Linear Algebra: Vector and Matrix Calculus · Throughout the book we profit from the convenience of vector and matrix notation and methods. This allows us to carry out the analysis of optimization problems involving two or more variables in a transparent way, without messy computations. A.1 INTRODUCTION The main advantage of linear algebra is conceptual. A collection of objects is viewed as one object, as a vector or as a matrix. This makes it often possible to write down data and formulas and to manipulate these in such a way that the structure is presented in a transparent way.