Computation of potentials used in the boundary element method Natalia Kolkovska An approximation to any harmonic function with known jumps across a smooth closed curve, such as the simple and double layer logarithmic potentials, is obtained as a solution to the discrete Laplacian on the rectangular domain. Exact integral representations of the discrete Laplacian are used in order to construct the right hand side of the difference equations. The error estimates are studied under the assumption that the harmonic function belongs to some Besov spaces.