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From: TideMan on 3 May 2010 16:03
On May 4, 6:05 am, "Truan Willis" <truan_wil...(a)hotmail.co.uk> wrote:
> Hi
>
> I would like to plot the logarithmic decrement of a structures transient vibration response signal so I can calculate its damping ratio.
>
> I can do it manual by simply looking through the data to identify the positive or negative amplitude peaks of the signal. However I have been unable to create an automated m-function to speed up the process.
>
> I've had a look through some of the peak finder functions that have been created but have been unable to apply them to my problem.
>
> Can anyone shed any light on how I might go about formulating an m-function to achieve this?
>
> Any help would be great
>
> Thanks
>
> Truan

You need to explain in more detail what you have tried and why it did
not work for your data.
Finding the positive and negative peaks in a 1-D signal is very easy -
5 lines of Matlab code.
What is so special about your data?

From: Truan Willis on 3 May 2010 17:25
TideMan <mulgor(a)gmail.com> wrote in message <f9be4cfc-e603-4de5-8f35-be750b51cd46(a)11g2000prv.googlegroups.com>...
> On May 4, 6:05 am, "Truan Willis" <truan_wil...(a)hotmail.co.uk> wrote:
> > Hi
> >
> > I would like to plot the logarithmic decrement of a structures transient vibration response signal so I can calculate its damping ratio.
> >
> > I can do it manual by simply looking through the data to identify the positive or negative amplitude peaks of the signal. However I have been unable to create an automated m-function to speed up the process.
> >
> > I've had a look through some of the peak finder functions that have been created but have been unable to apply them to my problem.
> >
> > Can anyone shed any light on how I might go about formulating an m-function to achieve this?
> >
> > Any help would be great
> >
> > Thanks
> >
> > Truan
>
> You need to explain in more detail what you have tried and why it did
> not work for your data.
> Finding the positive and negative peaks in a 1-D signal is very easy -
> 5 lines of Matlab code.
> What is so special about your data?

There's nothing special about my data. I've just been unable to find an obvious solution to my problem through the matlab help files. If you could point me in the right direction that would be great.
From: TideMan on 3 May 2010 19:35
On May 4, 9:25 am, "Truan Willis" <truan_wil...(a)hotmail.co.uk> wrote:
> TideMan <mul...(a)gmail.com> wrote in message <f9be4cfc-e603-4de5-8f35-be750b51c...(a)11g2000prv.googlegroups.com>...
> > On May 4, 6:05 am, "Truan Willis" <truan_wil...(a)hotmail.co.uk> wrote:
> > > Hi
>
> > > I would like to plot the logarithmic decrement of a structures transient vibration response signal so I can calculate its damping ratio.
>
> > > I can do it manual by simply looking through the data to identify the positive or negative amplitude peaks of the signal. However I have been unable to create an automated m-function to speed up the process.
>
> > > I've had a look through some of the peak finder functions that have been created but have been unable to apply them to my problem.
>
> > > Can anyone shed any light on how I might go about formulating an m-function to achieve this?
>
> > > Any help would be great
>
> > > Thanks
>
> > > Truan
>
> > You need to explain in more detail what you have tried and why it did
> > not work for your data.
> > Finding the positive and negative peaks in a 1-D signal is very easy -
> > 5 lines of Matlab code.
> > What is so special about your data?
>
> There's nothing special about my data. I've just been unable to find an obvious solution to my problem through the matlab help files. If you could point me in the right direction that would be great.

Browse through this thread. The code is there:
http://groups.google.com/group/comp.soft-sys.matlab/browse_thread/thread/cb4502239fb82010/bf18597ae8424c8d?lnk=gst&q=dirt#bf18597ae8424c8d

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