Zeros in a data set

  • Thread starter r4nd0m
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  • #1
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Hi,
does anyone know of some nice root-finding method (preferable GSL :-)) for a data set - i.e. I have a set of 3D data (x,y,z) where z = f(x,y,) and I want to know where the zeros of f are. I guess, I could write it myself with some interpolation method, but just in case someone knows...
 

Answers and Replies

  • #2
CRGreathouse
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If you have the function only in terms of triples, then the best you can do is search for:
1. Values of z which are actually equal to zero.
2. Sign changes from one value of z to the next.
 
  • #3
96
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yeah, but I'd like to know where exactly the points are, so the method I'm searching for should be using some kind of interpolation and then find the zeros.
 
  • #4
CRGreathouse
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Ah. Well this depends on the assumptions you make about the data. You could do a linear (or quadratic, or cubic, or some other polynomial) local fit/spline, or you could choose any of a number of other types of fits.

There's a free ("as in beer") program out there called CurveExpert that does this reasonably well, if you'd like to try it.
 

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