Solution of an inverse problem for the Helmholtz equation (Q1109997)

The Helmholtz equation in \(R^ n\) \(\Delta u+\omega^ 2c(x)u=-\delta\) is considered with radiation conditions on infinity. The uniqueness is demonstrated of the definition of a piecewise analytic function c(x) from the known values of the solution u(x,\(\omega)\) on \(\Omega \times (\omega_ 1,\omega_ 2)\), where \(\Omega\) is a domain in \(R^ n\) and \((\omega_ 1,\omega_ 2)\) is an interval of the real axis.