Dependencies among sections3 Chapter 1.Euclidean lines and hyperplanes5 Definition5 Euclidean plane and Euclidean space6 The standard scalar product9 Angles, orthogonality, and normal vectors14 Orthogonal projections and normality19 Projecting onto lines and hyperplanes containing zero19 Projecting onto arbitrary lines and hyperplanes24 Distances26 Reflections30 Reflecting in lines and hyperplanes containing zero31 Reflecting in arbitrary lines and hyperplanes33 Cauchy-Schwarz35 What is next?37 Chapter 2.Vector spaces41 Definition of a vector space42 Examples43 Basic properties50 Chapter 3.Subspaces53 Definition and examples53 The standard scalar product (again)56 Intersections58 Linear hulls, linear combinations, and generators60 Sums of subspaces65 Chapter 4.Linear maps71 Definition and examples71 Linear maps form a vector space76 Linear equations81 Characterising linear maps84 Isomorphisms86 Chapter 5.Matrices89 Definition of matrices90 Matrix associated to a linear map91 The product of a matrix and a vector92 Linear maps associated to matrices94 Addition and multiplication of matrices96 Row space, column space, and transpose of a matrix102 1 2CONTENTS Chapter 6.Computations with matrices105 Elementary row and column operations105 Row echelon form110 Generators for the kernel116 Reduced row echelon form119 Chapter 7.Linear independence and dimension123 Linear independence123 Bases129 The basis extension theorem and dimension135 Dimensions of subspaces143 Chapter 8.Ranks149 The rank of a linear map149 The rank of a matrix152 Computing intersections156 Inverses of matrices159 Solving linear equations164 Chapter 9.Linear maps and matrices167 The matrix associated to a linear map167 The matrix associated to the composition of linear maps171 Changing bases174 Endomorphisms175 Similar matrices and the trace176 Classifying matrices178 Similar matrices178 Equivalent matrices179 Chapter 10.Determinants183 Determinants of matrices183 Some properties of the determinant190 Cramer’s rule193 Determinants of endomorphisms194 Linear equations with parameters195 Chapter 11.Eigenvalues and Eigenvectors197 Eigenvalues and eigenvectors197 The characteristic polynomial199 Diagonalization203 Appendix A.Review of maps213 Appendix B.Fields215 Definition of fields215 The field of complex numbers.217 Appendix C.Labeled collections219 Appendix D.Infinite-dimensional vector spaces and Zorn’s Lemma22