A functional equation motivated by some trigonometric identities

作者：Fechner Wlodzimierz; Fechner Zywilla^*

来源：Journal of Mathematical Analysis and Applications, 2017, 449(2): 1160-1171.

DOI：10.1016/j.jmaa.2016.12.060

• Functional equation
• Trigonometric functions

We deal with the following functional equation:
f(xy) + lambda f(x)f(y) = phi(x, y),
where lambda is a complex number and f and phi are complex mappings defined on a semigroup. Moreover, we assume an addition formula of trigonometric type for phi. Our research is motivated by some earlier results related to a problem posed by S. Butler in 2003.

• 出版日期2017-5-15