This is a compilation of problems and solutions from past numerical methods qualifying exams at the University of Maryland.
Consider the system . The GMRES method starts with a point and normalizes the residual so that has 2-norm one. It then constructs orthonormal Krylov bases satisfying
where is a upper Hessenberg matrix. One then looks for an approximation to of the form
choosing so that is minimized, where is the usual Euclidean norm.
Show that minimizes .
We wish to show that