detcoef

1-D detail coefficients

collapse all in page

Syntax

D = detcoef(C,L)
D = detcoef(C,L,N)
D = detcoef(C,L,N,'cells')
[D1,…,Dp] = detcoef(C,L,N)

Description

D = detcoef(C,L) extracts the detail coefficients at the coarsest scale from the wavelet decomposition structure [C, L]. See wavedec for more information on C and L.

D = detcoef(C,L,N) extracts the detail coefficients at the level or levels specified by N.

D = detcoef(C,L,N,'cells') returns a cell array containing the detail coefficients. A minimum of two levels must be specified. The ith element of D contains the detail coefficients at the ith specified level.

  • If length(N)>1, the D = detcoef(C,L,N) is equivalent to D = detcoef(C,L,N,'cells').

  • D = detcoef(C,L,'cells') is equivalent to D = detcoef(C,L,[1:NMAX]), where NMAX = length(L)-2.

example

[D1,…,Dp] = detcoef(C,L,N) extracts the detail coefficients at the levels specified by N. The length of N must equal the number of output arguments.

Examples

collapse all

Open Live Script

This example shows how to obtain and plot the detail coefficients for an electrical current signal. This example uses zero-padding (see dwtmode).

Load the signal and select the first 3920 samples.

origmode = dwtmode('status','nodisplay');
dwtmode('zpd','nodisplay')

load leleccum; 
s = leleccum(1:3920);

Perform the decomposition at level 3 using db1. Extract the detail coefficients at levels 1, 2, and 3 from the decomposition structure.

[c,l] = wavedec(s,3,'db1');
[cd1,cd2,cd3] = detcoef(c,l,[1 2 3]);

Plot the original signal.

plot(s)
title('Original signal')
ylim([0 1000])

Plot the level 3 detail coefficients.

plot(cd3)
title('Level 3 detail coefficients (cd3)')
ylim([-60 60])

Plot the level 2 detail coefficients.

plot (cd2)
title('Level 2 detail coefficients (cd2)')
ylim([-60 60])

Plot the level 1 detail coefficients.

plot (cd1)
title('Level 1 detail coefficients (cd1)')
ylim([-60 60])

Restore the original extension mode.

dwtmode(origmode,'nodisplay')

Input Arguments

collapse all

Wavelet decomposition vector, specified as a real-valued vector. The vector C is the output of wavedec.

Bookkeeping vector, specified as a vector of positive integers. The bookkeeping vector L contains the number of coefficients by level. The bookkeeping vector is used to parse the coefficients in the wavelet decomposition vector C. The vectors C and L are the outputs of wavedec.

Detail level to extract from the wavelet decomposition, specified as a positive integer or a vector of positive integers.

  • If N is an integer, then N must be an integer such that 1 ≤ N ≤ NMAX, where NMAX = length(L)-2.

  • If N is a vector of integers, then N(j) must be an integer such that 1 ≤ N(j) ≤ NMAX, where j = 1,…,length(N).

Output Arguments

collapse all

Detail coefficients, returned as a real-valued vector or a cell array. If D is a cell array, the ith element of D are the detail coefficients at the level specified by the ith element of N.

Detail coefficients, returned as set of real-valued vectors. The ith output argument are the detail coefficients at the level specified by the corresponding element of N.

Extended Capabilities

C/C++ Code Generation
Generate C and C++ code using MATLAB® Coder™.

See Also

|

Introduced before R2006a

Wavelet Toolbox Documentation

Support