R help - Oct 2010 - Sine function fitting

Hi,

Is there a package to perform a sine function fitting to XY data?

Thx,
Ashz

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----------------------------------------
> Date: Mon, 18 Oct 2010 05:46:14 -0700
> From: ashz at walla.co.il
> To: r-help at r-project.org
> Subject: [R] Sine function fitting
>
>
> Hi,
>
> Is there a package to perform a sine function fitting to XY data?
Since no one replied AFAIK, are you asking about? FFT or something else?
It isn't really clear if you have 2D data or Y as a function of X.
I suppose that given some objective and a set of data, you could minimize
some error metric to fit your not-exactly-sinusoidal samples. You could
just peak-detect FFT as one approach and then you get a detailed
error analysis ( the spectrum). 


>
> Thx,
> Ashz
>
> --
> View this message in context:
http://r.789695.n4.nabble.com/Sine-function-fitting-tp3000156p3000156.html
> Sent from the R help mailing list archive at Nabble.com.

If you know the period of the sine that you want to fit (just fitting the
amplitude, phase shift, and offset) and are willing to assume normal errors (or
at least normal enough for the CLT) then you can just use the lm function.  If
you need to find the period as well (but still willing to assume normal enough
errors) then you can use the nls function.  You can approximate with splines and
lm for another approach.

No packages (other than the automatic ones) needed.

If you are not willing to assume normal enough errors, then we will need more
data to be able to help.

-- 
Gregory (Greg) L. Snow Ph.D.
Statistical Data Center
Intermountain Healthcare
greg.snow at imail.org
801.408.8111

> -----Original Message-----
> From: r-help-bounces at r-project.org [mailto:r-help-bounces at r-
> project.org] On Behalf Of ashz
> Sent: Monday, October 18, 2010 6:46 AM
> To: r-help at r-project.org
> Subject: [R] Sine function fitting
> 
> 
> Hi,
> 
> Is there a package to perform a sine function fitting to XY data?
> 
> Thx,
> Ashz
> 
> --
> View this message in context: http://r.789695.n4.nabble.com/Sine-
> function-fitting-tp3000156p3000156.html
> Sent from the R help mailing list archive at Nabble.com.
> 
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