An inverse problem of the wave equation for a general annular drum in with Robin boundary conditions

This paper is an extension to a recent work of E.M.E. Zayed and I.H. Abdel-Halim [Indian J Pure Appl Math, to appear]. The spectral function , where {μj}j=1∞ are the eigenvalues of the negative Laplacian in is studied for a variety o f domains, where −∞