Interlination of the functions of 2 variables on $M (M\geq2)$ straight lines with the highest algebraic accuracy

A general algorithm is proposed for constructing interlineation $\bar O_{MN}f(x)$, $x = (x_1,x_2)$  with the properties $$\frac{\partial ^s \bar O_{MN} f}{\partial v_k^s }\Bigg|_{\Gamma _k } = \frac{\partial ^s f}{\partial v_k^s }\Bigg|_{\Gamma _k } = {\varphi _{ks} (x)}\Bigg|_{\Gamma _...

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Bibliographic Details
Date:1992
Main Authors: Litvin, O.N., Литвин, А.Н.
Format: Article
Language:Russian
Published: Institute of Mathematics, NAS of Ukraine 1992
Online Access:https://umj.imath.kiev.ua/index.php/umj/article/view/8251
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Journal Title:Ukrains’kyi Matematychnyi Zhurnal
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Ukrains’kyi Matematychnyi Zhurnal
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Summary:A general algorithm is proposed for constructing interlineation $\bar O_{MN}f(x)$, $x = (x_1,x_2)$  with the properties $$\frac{\partial ^s \bar O_{MN} f}{\partial v_k^s }\Bigg|_{\Gamma _k } = \frac{\partial ^s f}{\partial v_k^s }\Bigg|_{\Gamma _k } = {\varphi _{ks} (x)}\Bigg|_{\Gamma _k } ,k = \overline {1,M}; s = \overline {0,N} , $$ $$\bar O_{MN} x^\alpha \equiv x^\alpha ,0 \leq |\alpha | = \alpha _1 + \alpha _2 \leq M(N + 1) - 1, x^\alpha = x_1^{\alpha _1 } x_2^{\alpha _2 } ,$$ where ${\Gamma _k }$  is a given set of lines of arbitrary disposition on the plane $Ox_1x_2$, $v_k \bot \Gamma_k$. An integral representation is derived of the residual of approximation of the function $f(x)$ by the operators $\bar O_{MN} f(x)$. Examples are considered of interlineation operators preserving the class $C^r(R^2)$, and also operators not preserving the differentiability class, to which the function $f(x)$ belongs.