Finite difference techniques classical schemes

It should be emphasized that averaging technique does not require the grid to be small compared to the layering. These results can be considered as an outgrowth of the integro-interpolation finite-difference schemes. This term first appeared in the Russian literature in the papers of Tikhonov and Samarsky in the 1960 s (in Western literature the closest related technique is called the external approximation). However, only conformal variations of conductivity were treated in the classical integro-interpolation method. 

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