The final test will be based on all material we covered during the semester. However, proofs of theorems (or parts of theorems) will be restricted to those covered after the midterm. Everything else (definitions and problems) will cover all the material we studied. So, the midterm preparation guide (minus proofs of theorems from the book) should be considered a part of this guide. Below I will list only new material. In addition to the theoretical material from the book, there will be some other problems, not listed here. Definitions and notions: ======================== Floating point axioms ( (13.5) and (13.7) ) Stability of an algorithm Backward stability of an algorithm Positive definite matrix Eigenvalue, eigenvector, eigenspace, spectrum Characteristic polynomial Geometric multiplicity, algebraic multiplicity Similarity transformation Eigenvalue decomposition (diagonalization) Defective eigenvalue, defective matrix Diagonalizable matrix Trace of a matrix Schur factorization Hessenberg matrix Rayleigh quotient Things to prove: ================ Given an m-by-n complex matrix A, and vector b, prove that the value of the 2-norm of the residual r=Ax-b is minimized when Ax=Pb, where P is the orthogonal projector onto the range of A Describe steps in the Householder triangularization algorithm Thms 15.1, 16.2, 16.3. Thm 17.1, case m=2 Give example of instability of LU decomposition (and explain how this instability manifests itself). Describe in details the LU decomposition algorithm without pivoting. Prove the properties of the elementary matrices that enable this simple algorithm (the first two "strokes of luck"). Prove that is A is a Hermitian positive definite matrix, then X*AX is also Hermitian positive definite. (Here X is m by n matrix, m greater or equal than n, full rank. X* is the adjoint of X.) Prove that any principal submatrix of a positive definite matrix is also positve definite. Prove that every Hermitian positive definite matrix has a Cholesky decomposition (one induction step is enough). Prove thms: 24.3 24.4 24.5 24.6 24.9 27.1 28.1 Give an example of a defective matrix, with an explanation Show that in the case of a real symmetric matrix the eigenvectors are the stationary points of the Rayleigh quotient. (compute the gradient). Describe reduction to the Hessenberg form. (Here and below "describe" means: give the details of the algorithm and explain how and why it works.) Describe: power iteration, inverse iteration, Rayleigh quotient iteration.