Favard Operator
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In
functional analysis Functional analysis is a branch of mathematical analysis, the core of which is formed by the study of vector spaces endowed with some kind of limit-related structure (e.g. Inner product space#Definition, inner product, Norm (mathematics)#Defini ...
, a branch of
mathematics Mathematics is an area of knowledge that includes the topics of numbers, formulas and related structures, shapes and the spaces in which they are contained, and quantities and their changes. These topics are represented in modern mathematics ...
, the Favard operators are defined by: : mathcal_n(f)x) = \frac \sum_^\infty where x\in\mathbb, n\in\mathbb. They are named after
Jean Favard Jean Favard (28 August 190221 January 1965) was a French mathematician who worked on analysis. Favard was born in Peyrat-la-Nonière. During World War II he was a prisoner of war in Germany. He also was a President of the French Mathematical So ...
.


Generalizations

A common generalization is: : mathcal_n(f)x) = \frac \sum_^\infty where (\gamma_n)_^\infty is a positive sequence that converges to 0. This reduces to the classical Favard operators when \gamma_n^2=1/(2n).


References

* This paper also discussed Szász–Mirakyan operators, which is why Favard is sometimes credited with their development (e.g. Favard–Szász operators


Footnotes

Approximation theory {{mathanalysis-stub