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Multidimensional curve fitting [message #4256] Fri, 19 May 1995 00:00 Go to previous message
keith is currently offline  keith
Messages: 7
Registered: July 1993
Junior Member
I have a 2-dimensional dataset which I wish to parameterize with a
scalar function of 2 variables in the form y=f(x1,x2) (and in the
future I will extend this to higher dimensionalities). I would prefer
a nonlinear function f(), but could make do with a polynomial of
smallish order (<5).

The usual IDL fitting routines svdfit and curvefit only deal with 1-d
functions. There is a function "sfit" which claims to perform surface
fitting, but this can not provide uncertainties in the fit, nor even
take account of the numerical values of x1, x2.

The JHU usr library funtion opfit2d doesn't really do what I want
either. Although orthogonal polynomials are nice, I need the
"ordinary" polynomial coefficients in order to taka analytical
derivatives.

Do any of you have ideas/suggestions/routines which might help?

Thanks

Keith Refson
--
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| Email : keith@earth.ox.ac.uk | Dr Keith Refson, Dept of Earth Sciences|
| TEL(FAX): +44 1865 272026 (272072)| Parks Road, Oxford OX1 3PR, UK |
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