Discrete Wavelet analysis code problem

Hi

So, I'm trying to code a program that computes and displays the Discrete wavelet analysis over a certain number of levels of an imported signal using the wavedec function. But I have a problem running it so far since I've got these 2 errors :

Error using appcoef (line 39)
Invalid level value.

Error in Ondelette (line 12)
ap4=appcoef(c,1,'db2',4);

The code is as shown below :

clear all ;
close all ;
clc ;

s = dlmread('I1V1500.txt','\t'); 
whos
sig = s ;
longsig=length(sig);

[c.l]=wavedec(sig,4,'db2');

ap4=appcoef(c,1,'db2',4);
ap3=appcoef(c,1,'db2',3);
ap2=appcoef(c,1,'db2',2);
ap1=appcoef(c,1,'db2',1);
d4=detcoef(c,l,4);
d3=detcoef(c,l,3);
d2=detcoef(c,l,2);
d1=detcoef(c,1,1);
figure ;
subplot(5.2,1);plot(sig);

I've also joined the imported file in question.

I'd be grateful if someone could help me solve my problem.

Thanks in advance

[Sebsatien]

Any help please ?

Answer 1

[Walter Roberson]

[c.l]=wavedec(sig,4,'db2');

should be

[c, L]=wavedec(sig,4,'db2');

You were accidentally outputting to a structure field instead of to two different variables.

And

ap4=appcoef(c,1,'db2',4);
ap3=appcoef(c,1,'db2',3);
ap2=appcoef(c,1,'db2',2);
ap1=appcoef(c,1,'db2',1);

should be

ap4=appcoef(c,L,'db2',4);
ap3=appcoef(c,L,'db2',3);
ap2=appcoef(c,L,'db2',2);
ap1=appcoef(c,L,'db2',1);

You were passing in the digit 1 instead of the letter lower-case L.