On the stability of a class of cosine type functional equations

Driss Zeglami


The aim of this paper is to investigate the stability problem for the pexiderized trigonometric functional equation

    f₁(xy)+f₂(xσ(y))=2g₁(x)g₂(y),  x,y∈G,  

where G is an arbitrary group, f₁,f₂,g₁ and g₂ are complex valued functions on G and σ is an involution of G. Results of this paper also can be extended to the setting of monoids (that is, a semigroup with identity) that need not be abelian.


stability, Superstability, d'Alembert equation, trigonometric functional equation.

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DOI: http://dx.doi.org/10.5269/bspm.v37i2.29563

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