Explicit estimation of an integral in a domain by the multiple reciprocity method with the use of inverse operations

The paper presents two methods of solving the Poisson equation. One is based on the multiple reciprocity method. An analytical form of the basic solution obtained by means of inverse operation technique enabled assessing the method's error. The other is based on source function expansion into a series according to polyharmonic functions. Further polyharmonic functions have been obtained through inverse operations (with the delta -1 operator) applied to polyharmonic functions. Numerical results have confirmed perfect efficiency of both methods.