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Thread Subject:
Wavelet: Coefficient Maximum at the beginning and end of the signal

Subject: Wavelet: Coefficient Maximum at the beginning and end of the signal

From: Sebastian Gatzka

Date: 11 Mar, 2011 11:53:05

Message: 1 of 4

Hello World.

I'm observing coefficient maxima at the beginning and the end of my signal:
http://therealsega.th.funpic.de/glr/cwt.png

Any ideas what may be the problem?!

Thanks.
Sebastian

Subject: Wavelet: Coefficient Maximum at the beginning and end of the signal

From: Wayne King

Date: 11 Mar, 2011 12:17:04

Message: 2 of 4

"Sebastian Gatzka" <sebastian.gatzka.NOSPAM@stud.tu-darmstadt.de> wrote in message <ild2f1$pqn$1@fred.mathworks.com>...
> Hello World.
>
> I'm observing coefficient maxima at the beginning and the end of my signal:
> http://therealsega.th.funpic.de/glr/cwt.png
>
> Any ideas what may be the problem?!
>
> Thanks.
> Sebastian

Hi Sebastian, Those are just edge effects as a result of the fact that you are necessarily dealing with a finite length vector.

Wayne

Subject: Wavelet: Coefficient Maximum at the beginning and end of the signal

From: Sebastian Gatzka

Date: 11 Mar, 2011 13:33:05

Message: 3 of 4

"Wayne King" <wmkingty@gmail.com> wrote in message <ild3s0$pnk$1@fred.mathworks.com>...
> "Sebastian Gatzka" <sebastian.gatzka.NOSPAM@stud.tu-darmstadt.de> wrote in message <ild2f1$pqn$1@fred.mathworks.com>...
> > Hello World.
> >
> > I'm observing coefficient maxima at the beginning and the end of my signal:
> > http://therealsega.th.funpic.de/glr/cwt.png
> >
> > Any ideas what may be the problem?!
> >
> > Thanks.
> > Sebastian
>
> Hi Sebastian, Those are just edge effects as a result of the fact that you are necessarily dealing with a finite length vector.
>
> Wayne

Thank you Wayne.
Now I know what I'm dealing with.

Subject: Wavelet: Coefficient Maximum at the beginning and end of the signal

From: Wayne King

Date: 11 Mar, 2011 13:50:05

Message: 4 of 4

"Sebastian Gatzka" <sebastian.gatzka.NOSPAM@stud.tu-darmstadt.de> wrote in message <ild8ah$doi$1@fred.mathworks.com>...
> "Wayne King" <wmkingty@gmail.com> wrote in message <ild3s0$pnk$1@fred.mathworks.com>...
> > "Sebastian Gatzka" <sebastian.gatzka.NOSPAM@stud.tu-darmstadt.de> wrote in message <ild2f1$pqn$1@fred.mathworks.com>...
> > > Hello World.
> > >
> > > I'm observing coefficient maxima at the beginning and the end of my signal:
> > > http://therealsega.th.funpic.de/glr/cwt.png
> > >
> > > Any ideas what may be the problem?!
> > >
> > > Thanks.
> > > Sebastian
> >
> > Hi Sebastian, Those are just edge effects as a result of the fact that you are necessarily dealing with a finite length vector.
> >
> > Wayne
>
> Thank you Wayne.
> Now I know what I'm dealing with.

Good Sebastian, I see from your first post to your latest message you are making good progress in learning the tools. You might also be interested in reading up on the cone of influence for the CWT, which is implemented in conofinf() in MATLAB.

Also, if you have access to the R2011a prerelease version of MATLAB, there is a new routine for the CWT using a Fourier transform algorithm. That method has an inverse CWT associated with it, so you can reconstruct an approximation to your original signal based on select scales.

Wayne

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