Typically, Q is presumed symmetric, in which case its gradient is 2x'Q, and its eigenvalues are real. More generally, there could be quadratic constraint functions. Quasiconcave function . Negative is quasiconvex . Quasiconvex function .
Level sets are convex .
Quasi-Newton method . One designed to capture the essence of the modified Newton's method , such as the Broyden family . The general idea is to build up an approximation to the inverse hessian to get an order of convergence between 1 and 2. Beginning of glossary , Notation , Supplements .