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Topic: Linear extrapolation
Replies: 5   Last Post: May 15, 2014 2:39 PM

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Barry Williams

Posts: 311
Registered: 6/14/06
Re: Linear extrapolation
Posted: May 15, 2014 2:39 PM
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dpb <none@non.net> wrote in message <ll2phs$6h3$1@speranza.aioe.org>...
> On 5/15/2014 10:28 AM, Paulo Oliveira wrote:
> > Hi Steve,
> > I try your idea, but I have only matrix with this values, How can obtain
> > the vector to calculate the extrapolation values in interp1.
> >
> > Thanks for your attention.

>
> Gotta' make 'em up...one would then presume lacking anything for the
> others, 1:N for the length N would be a good start...
>
> --


Paulo, I think what Steve and dpb are trying to tell you is that no one here is going to be able to offer you much help without additional information about the data in your matrix or array. Is there an underlying function? How noisy are the data? If there is an underlying function and the data are not too noisy, then you may be better off to use a function like polyfit, robustfit, or nlinfit and extrapolating that way. If you truly want or need to use interp1, then good luck. It may work if the data are fairly monotonic and the interpolated points aren't too far from the measured data.
Barry



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