\input zb-basic \input zb-ioport \iteman{io-port 03833245} \itemau{Kaporin, I.E.} \itemti{On the problem of the solution of the Poisson difference equation in an incomplete-sparse formulation.} \itemso{Difference methods of mathematical physics. Theory of numerical methods, Work Collect., Moskva 1981, 13-22 (1981).} \itemcc{} \itemut{marching algorithm; Fourier-sine transform; difference equations; efficiency of algorithms; Poisson equation} \itemli{} \end