A brief survey is given to show that harmonic averages enter in a natural way in the numerical solution of various variable coefficient problems, such as in elliptic and transport equations, also of singular perturbation types. Local Green’s functions used as test functions in the Petrov-Galerkin finite element method combined with harmonic averages can be very efficient and are related to exact difference schemes.
2
Dostęp do pełnego tekstu na zewnętrznej witrynie WWW
Consider the first order linear difference equation with general advanced argument and variable coefficients of the form $$\nabla x(n) - p(n)x(\tau (n)) = 0, n \geqslant 1,$$ where {p(n)} is a sequence of nonnegative real numbers, {τ(n)} is a sequence of positive integers such that $$\tau (n) \geqslant n + 1, n \geqslant 1,$$ and ▿ denotes the backward difference operator ▿x(n) = x(n) − x(n − 1). Sufficient conditions which guarantee that all solutions oscillate are established. Examples illustrating the results are given.
JavaScript jest wyłączony w Twojej przeglądarce internetowej. Włącz go, a następnie odśwież stronę, aby móc w pełni z niej korzystać.