... Th.eorie des Distributions, Hermann, Paris, 1978 Received March 20, 2000 Revised January 5, 2001 Institute of Mathematics, NCST of Vietnam ... constant C is independent of hand u(x) REFERENCES [I] G.1 Marchuk, Mathematical Modelling in the Environment Problems, Nau ka, Moscow, 1982 (Russian) [2] V S Vlad irnirov , Generalized Functions ... 35 (2) (1998) 43S-4S2 [6] Hoang Dinh Dung, Difference schemes for generalized solutions of some elliptic differential equations, I, Journal of Computer Science and Cuberneiics 15 (1) (1999) 49-61...