Open Access

On the Superstability Related with the Trigonometric Functional Equation

Advances in Difference Equations20092009:503724

Received: 22 August 2009

Accepted: 6 November 2009

Published: 10 November 2009


We will investigate the superstability of the (hyperbolic) trigonometric functional equation from the following functional equations: , , , , which can be considered the mixed functional equations of the sine function and cosine function, of the hyperbolic sine function and hyperbolic cosine function, and of the exponential functions, respectively.

Publisher note

To access the full article, please see PDF

Authors’ Affiliations

Department of Mathematics, Kangnam University, Youngin, South Korea


© Gwang Hui Kim. 2009

This article is published under license to BioMed Central Ltd. This is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.