Estimating the Quadratic Form xTA?mx for Symmetric Matrices: Further Progress and Numerical Computations

In this paper, we study estimates for quadratic forms of the type xTA?mx, m?N, symmetric matrices. We derive a general approach estimating form and present some upper bounds corresponding absolute error. Specifically, consider three different approaches xTA?mx. The first is based on projection method, second minimization procedure, last heuristic. Numerical examples showing effectiveness are presented. Furthermore, compare behavior proposed with other methods that derived in literature.