Cosine-sine functional equation on semigroups
General Mathematics
2023-06-09 v1
Abstract
Let be a semigroup. We determine the complex-valued solutions of the functional equation \begin{equation*}f(xy)=f(x)g(y)+g(x)f(y)+h(x)h(y), x,y\in S,\end{equation*} in terms of multiplicative functions, solutions of the special case of the sine addition law, where is a multiplicative function, and also in terms of solutions of the particular case of the cosine-sine functional equation where is a multiplicative function and such that the pair satisfies the sine addition law.
Cite
@article{arxiv.2306.04666,
title = {Cosine-sine functional equation on semigroups},
author = {Omar Ajebbar and Elhoucien Elqorachi},
journal= {arXiv preprint arXiv:2306.04666},
year = {2023}
}