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From: Aino on 2 Jun 2010 20:04
Hello,

I am trying to accomplish the same as george. I have found several codes that all claim that they calculate signal entropy, but interestingly I haven't been able to calculate the same or even closely the same entropy with the codes.

That previous link to Matlab's signal entropy won't help me, but the m-file would. Unfortunately my Matlab has also a function called entropy, but it is for a greyscale picture:

http://www.mathworks.com/access/helpdesk/help/toolbox/images/entropy.html

Could anyone please tell me where I could get that Matlab's signal entropy m-file that Sprinceana pointed out?

Thank you,
Aino


"Sprinceana " <mihaispr(a)yahoo.com> wrote in message <h0hc1l$li7$1(a)fred.mathworks.com>...
> "george " <qwerty6542(a)yahoo.gr> wrote in message <h0hb3l$k76$1(a)fred.mathworks.com>...
> > How can I compute entropy?not to an image but to a signal?
>
> Here is a link that can help you:
>
> http://www.cs.rug.nl/~rudy/matlab/doc/entropy.html
From: Walter Roberson on 2 Jun 2010 20:16
Aino wrote:

> Could anyone please tell me where I could get that Matlab's signal
> entropy m-file that Sprinceana pointed out?

The link to the source was at the bottom of that page:

http://www.cs.rug.nl/~rudy/matlab/source/entropy.m

Note that that is not a Mathworks file: it was written by Rudy Moddemeijer
http://www.cs.rug.nl/~rudy/matlab/
From: Aino on 2 Jun 2010 20:24
Wow,

I must have been blind.. Thank you. :)

-Aino

Walter Roberson <roberson(a)hushmail.com> wrote in message <PvCNn.39391$Ak3.37102(a)newsfe16.iad>...
> Aino wrote:
>
> > Could anyone please tell me where I could get that Matlab's signal
> > entropy m-file that Sprinceana pointed out?
>
> The link to the source was at the bottom of that page:
>
> http://www.cs.rug.nl/~rudy/matlab/source/entropy.m
>
> Note that that is not a Mathworks file: it was written by Rudy Moddemeijer
> http://www.cs.rug.nl/~rudy/matlab/
From: Aino on 2 Jun 2010 20:51
So, just to be safe, it is reasonable that the following signal has an entropy of 2.1472?:

y=1*sin(2*[1:100])+2*sin(0.5*[1:100]).^2+3*sin(0.1*[1:100]);

This is what I got using that code. I feel that entropy seems a rather random measure..

-Aino


"Aino" <aino.tietavainen(a)removeThis.helsinki.fi> wrote in message <hu6snl$c8q$1(a)fred.mathworks.com>...
> Wow,
>
> I must have been blind.. Thank you. :)
>
> -Aino
>
> Walter Roberson <roberson(a)hushmail.com> wrote in message <PvCNn.39391$Ak3.37102(a)newsfe16.iad>...
> > Aino wrote:
> >
> > > Could anyone please tell me where I could get that Matlab's signal
> > > entropy m-file that Sprinceana pointed out?
> >
> > The link to the source was at the bottom of that page:
> >
> > http://www.cs.rug.nl/~rudy/matlab/source/entropy.m
> >
> > Note that that is not a Mathworks file: it was written by Rudy Moddemeijer
> > http://www.cs.rug.nl/~rudy/matlab/
From: Walter Roberson on 3 Jun 2010 00:02
Aino wrote:
> So, just to be safe, it is reasonable that the following signal has an
> entropy of 2.1472?:
>
> y=1*sin(2*[1:100])+2*sin(0.5*[1:100]).^2+3*sin(0.1*[1:100]);
>
> This is what I got using that code. I feel that entropy seems a rather
> random measure..

Sorry, no idea; it would take me a bit of time to work that out, and I'd
probably be using a different entropy measure.
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