RUS  ENG
Full version
JOURNALS // Matematicheskii Sbornik // Archive

Mat. Sb. (N.S.), 1974 Volume 94(136), Number 1(5), Pages 126–151 (Mi sm3661)

This article is cited in 4 papers

On a point source in an inhomogeneous medium

B. R. Vainberg


Abstract: Let $L\bigl(x,\frac\partial{\partial x}\bigr)$, $x\in\mathbf R^n$, be a second-order elliptic differential operator coinciding with the Laplace operator in a neighborhood of infinity. Let $E$ be the Green's function of the Cauchy problem for the operator $\frac{\partial^2}{\partial t^2}-L$. Under certain assumptions regarding the trajectories of the Hamiltonian system connected with the operator in question, the following results are obtained: 1) an asymptotic approximation with respect to smoothness $E_N$ to the function $E$ is constructed by Hadamard's method; 2) we show that the Fourier transformation of $E_N$ from $t$ to $k$ is an analytic function of $k$ in the complex plane with a cut along the negative part of the imaginary axis, and with $\lvert\operatorname{Im}k\rvert<C<\infty$ and $\lvert\operatorname{Re}k\rvert\to\infty$ it gives the asymptotic behavior of the fundamental solution of the operator $-L-k^2$; 3) the asymptotic behavior as $t\to\infty$ of the solutions of the nonstationary problem is obtained.
Bibliography: 44 titles.

UDC: 517.944

MSC: Primary 35L15, 35B40, 35A35; Secondary 35A22, 35P25

Received: 26.06.1973


 English version:
Mathematics of the USSR-Sbornik, 1974, 23:1, 123–148

Bibliographic databases:


© Steklov Math. Inst. of RAS, 2026