Approximation of Bivariate Functions via Smooth Extensions

For a smooth bivariate function defined on a general domain with arbitrary shape, it is difficult to do Fourier approximation or wavelet approximation. In order to solve these problems, in this paper, we give an extension of the bivariate function on a general domain with arbitrary shape to a smooth...

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Main Author: Zhihua Zhang
Format: Article
Language:English
Published: Wiley 2014-01-01
Series:The Scientific World Journal
Online Access:http://dx.doi.org/10.1155/2014/102062
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author Zhihua Zhang
author_facet Zhihua Zhang
author_sort Zhihua Zhang
collection DOAJ
description For a smooth bivariate function defined on a general domain with arbitrary shape, it is difficult to do Fourier approximation or wavelet approximation. In order to solve these problems, in this paper, we give an extension of the bivariate function on a general domain with arbitrary shape to a smooth, periodic function in the whole space or to a smooth, compactly supported function in the whole space. These smooth extensions have simple and clear representations which are determined by this bivariate function and some polynomials. After that, we expand the smooth, periodic function into a Fourier series or a periodic wavelet series or we expand the smooth, compactly supported function into a wavelet series. Since our extensions are smooth, the obtained Fourier coefficients or wavelet coefficients decay very fast. Since our extension tools are polynomials, the moment theorem shows that a lot of wavelet coefficients vanish. From this, with the help of well-known approximation theorems, using our extension methods, the Fourier approximation and the wavelet approximation of the bivariate function on the general domain with small error are obtained.
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publishDate 2014-01-01
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spelling doaj-art-8187b003559341bea19d63d8930085e12025-02-03T01:28:41ZengWileyThe Scientific World Journal2356-61401537-744X2014-01-01201410.1155/2014/102062102062Approximation of Bivariate Functions via Smooth ExtensionsZhihua Zhang0College of Global Change and Earth System Science, Beijing Normal University, Beijing 100875, ChinaFor a smooth bivariate function defined on a general domain with arbitrary shape, it is difficult to do Fourier approximation or wavelet approximation. In order to solve these problems, in this paper, we give an extension of the bivariate function on a general domain with arbitrary shape to a smooth, periodic function in the whole space or to a smooth, compactly supported function in the whole space. These smooth extensions have simple and clear representations which are determined by this bivariate function and some polynomials. After that, we expand the smooth, periodic function into a Fourier series or a periodic wavelet series or we expand the smooth, compactly supported function into a wavelet series. Since our extensions are smooth, the obtained Fourier coefficients or wavelet coefficients decay very fast. Since our extension tools are polynomials, the moment theorem shows that a lot of wavelet coefficients vanish. From this, with the help of well-known approximation theorems, using our extension methods, the Fourier approximation and the wavelet approximation of the bivariate function on the general domain with small error are obtained.http://dx.doi.org/10.1155/2014/102062
spellingShingle Zhihua Zhang
Approximation of Bivariate Functions via Smooth Extensions
The Scientific World Journal
title Approximation of Bivariate Functions via Smooth Extensions
title_full Approximation of Bivariate Functions via Smooth Extensions
title_fullStr Approximation of Bivariate Functions via Smooth Extensions
title_full_unstemmed Approximation of Bivariate Functions via Smooth Extensions
title_short Approximation of Bivariate Functions via Smooth Extensions
title_sort approximation of bivariate functions via smooth extensions
url http://dx.doi.org/10.1155/2014/102062
work_keys_str_mv AT zhihuazhang approximationofbivariatefunctionsviasmoothextensions