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appcoef

1-D近似系数

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Syntax

a = appcoef（c，l，wname）
a = appcoef（c，l，lor，hir）
A = appcoef(___,N)

Description

A= appcoef(C,L,wname)使用小波分解结构[C,L] of a 1-D signal and the wavelet specified bywname。（看wavedec了解更多信息。）

A= appcoef(C,L,LoR,HiR)uses the lowpass reconstruction filterLoR和highpass reconstruction filterHiR。（看wfilters了解更多信息。）

example

A= appcoef(___,N)returns the approximation coefficients at levelN。If [C,L] is theM-level wavelet decomposition structure of a 1-D signal, then0 ≤ N ≤ M。

Examples

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打开实时脚本

This example shows how to extract the level 3 approximation coefficients.

Load the signal consisting of electricity usage data.

loadLeleccum; sig = leleccum(1:3920);

Obtain the DWT down to level 5 with the'sym4'小波。

[C,L] = wavedec(sig,5,'sym4');

提取级别3近似系数。绘制原始信号和近似系数。

lev = 3;a3 = appcoef（c，l，'sym4',Lev); subplot(2,1,1) plot(sig); title(“原始信号”); subplot(2,1,2) plot(a3); title('Level-3 Approximation Coefficients');

Figure contains 2 axes objects. Axes object 1 with title Original Signal contains an object of type line. Axes object 2 with title Level-3 Approximation Coefficients contains an object of type line.

您可以用1到5的任何值代替利夫to obtain the approximation coefficients for the corresponding level.

Input Arguments

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小波分解矢量of a 1-D signal, specified as a real-valued vector.Cis the output ofwavedec。The bookkeeping vectorL用于按级别解析小波分解矢量中的系数。

Example:[C,L] = wavedec(randn(1,256),4,'coif1')返回4层小波decomposition of a vector.

Data Types:single|double
Complex Number Support:Yes

Bookkeeping vector of the wavelet decomposition of a 1-D signal, specified as a vector of positive integers. The bookkeeping vector is used to parse the coefficients in the wavelet decomposition vectorCby level.

Example:[C,L] = wavedec(randn(1,256),4,'coif1')返回4层小波decomposition of a vector.

Data Types:single|double

Wavelet used to generate the wavelet decomposition of a 1-D signal, specified as a character vector or string scalar. The wavelet is from one of the following wavelet families: Daubechies, Coiflets, Symlets, Fejér-Korovkin, Discrete Meyer, Biorthogonal, and Reverse Biorthogonal. Seewavemngr对于每个家庭可用的小波。

Example:'db4'

Wavelet lowpass reconstruction filter, specified as an even-length real-valued vector.LoR必须与HiR。LoR必须是与用于创建小波分解结构的小波相关的低通重建过滤器[C,L]。（看wfilters了解更多信息。）

Wavelet highpass reconstruction filter, specified as an even-length real-valued vector.HiR必须与LoR。HiR必须是与用于创建小波分解结构的小波相关的高通重建过滤器[C,L]。（看wfilters了解更多信息。）

Approximation coefficients level, specified as a positive integer. If [C,L] is theM-level wavelet decomposition structure of a 1-D signal, then0 ≤ N ≤ M。

Output Arguments

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Approximation coefficients at levelN，作为实价矢量返回。

Algorithms

The input vectorsC和Lcontain all the information about the signal decomposition.

让NMAX = length(L)-2; thenc = [a（nmax）d（nmax）... d（1）]whereA和theDare vectors. IfN = NMAX, then a simple extraction is done; otherwise,appcoef使用反波变换迭代地计算近似系数。

Extended Capabilities

Version History

在R2006a之前引入

See Also

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