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Re: Smooth line approximating minima of a data series
From: |
Olaf Till |
Subject: |
Re: Smooth line approximating minima of a data series |
Date: |
Wed, 24 Feb 2010 11:23:06 +0100 |
User-agent: |
Mutt/1.5.18 (2008-05-17) |
On Wed, Feb 24, 2010 at 09:04:07AM +0100, Matthias Brennwald wrote:
> Dear all
>
> Consider a series of data values that reflect a smooth function (e.g.
> a low-degree polynomial), but there might be additional features in
> the data (e.g. narrow peaks or noise). I'd like to fit a polynomial to
> this data, whereby this polynomial reflects a smooth approximation of
> the minima of the raw data (I call this the "base line"). The
> following might help to illustrate what I'm trying to accomplish:
>
> x = [-1:0.01:1]; % x-axis values
> p = [-3 2 1 0]; yp = polyval (p,x); % make up a polynomial
> reflecting the "base line" for illustration
> y = yp + rand(size(x)); % this would be the raw data
> plot (x,y,x,yp); legend ('raw data','base line') % plot the raw
> data and the polynomial for illustration
>
> Has anyone an idea of how to accomplish this? Are there standard
> methods?
What about polyfit?
Olaf
Re: Smooth line approximating minima of a data series, Ben Abbott, 2010/02/24