computing cwt only at scale 5

I want to compute cwt at scale 5 to detect local maxima at this scale so I did this : cfs = cwt(x,5,'haar'); plot(cfs); Is my program correct or I need to use all scales from 1 to 5?

Answer 1

[Wayne King]

Hi Claire, yes, your code is correct, but are you sure you don't want to include at least a few more scales?

That can help in identifying local maxima lines:

   load cuspamax;
   x = 1:length(cuspamax);
   scales = 1:32;
   cfs = cwt(cuspamax,scales,'haar');
   [lmaxima,indices] = localmax(cfs,[],false);
   [iRow,iCol] = find(lmaxima);
   subplot(211);
   imagesc(abs(cfs)); axis xy;
   axis([1 1024 1 32]);
   ylabel('Scale'); title('CWT Coefficients (Moduli)');
   subplot(212);
   plot(x(iCol),scales(iRow),'marker','o','markerfacecolor',[0 0 1],...
       'linestyle','none');
   xlabel('Position'); ylabel('Scale'); title('Maxima Lines');
   axis([1 1024 1 32]);

[claire]

Thanks for answering me, did you choose scale 32 for a particular reason?

[Wayne King]

No, Claire just as an example.

[Jean-Luc Bruyelle]

How do we choose the appropriate scales using the same function ?