Re: Harmonic analysis

[Ansley Manke <Ansley.B.Manke@xxxxxxxx>]

Hi everyone,
The FFT functions in Ferret do not compute a confidence interval.
The functions were originally written as external functions, and that
code is available from the Ferret External Functions webpage,
http://ferret.pmel.noaa.gov/Ferret/External_Functions/

Look for the links to code, i.e.
http://ferret.pmel.noaa.gov/Ferret/External_Functions/external_EF_code_contents.html
http://ferret.pmel.noaa.gov/Ferret/External_Functions/internal_EF_code_contents.html

If anyone has code to compute confidence intervals for FFT's and
would like to contribute such a function, it would be very much
appreciated!

Ansley Manke

Gabriel Clauzet wrote:

> Hi all,
>
> I'm using this script to calculate the power spectrum of time series wich
> work quite well.
> I would like to compute the confidence interval with the spectrum. Does
> anybody know if it is possible using ferret ?
>
> Thanks in advance.
>
> Regards,
> Gabriel
>
> ----- Original Message -----
> From: "Ansley Manke" <Ansley.B.Manke@noaa.gov>
> To: <kvram55@yahoo.com>
> Cc: "Ansley Manke" <ansley@pmel.noaa.gov>;
> <ferret_users@ferret.wrc.noaa.gov>
> Sent: Friday, March 28, 2003 6:13 PM
> Subject: Re: Harmonic analysis
>
> > Hi Ramesh,
> > Ferret has a  family of FFT functions; see the demo
> > ef_fft_demo.jnl for a simple example of their use
> >
> > http://www.ferret.noaa.gov/Ferret/Demos/ef_fft_demo/ef_fft_demo.html
> >
> > In the Users Guide, under FFTA, there is a discussion of the
> > method that the functions use.  Note that in addition to the FFT
> > amplitude and phase that are used in the demo, there are also
> > functions to return the real and imaginary part of the transformation,
> > and to invert the Fourier transform.   If you develop Ferret scripts
> > to use these functions for your analysis, they would be welcome
> > contributions to the Ferret community.
> >
> > Ansley Manke
> >
> > "K.V. Ramesh" wrote:
> >
> > >  Dear Ferret users,
> > >    Is it possible to perform harmonic analysis using ferret,
> > > to find different hormonics from daily data. If so How can
> > > I do it. Can any body can help me.
> > >
> > > Thanks in advance.
> > >
> > > regards,
> > > Ramesh
> > >
> > > __________________________________________________
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> >
> > --
> > Ansley Manke  Pacific Marine Environmental Laboratory  Seattle WA
> (206)526-6246
> >
> >
> >
> >

--
Ansley Manke  Pacific Marine Environmental Laboratory  Seattle WA  (206)526-6246