| sigma in curvefit function! [message #39349] |
Thu, 13 May 2004 08:33 |
<Raquel.Niclos
Messages: 1
Registered: May 2004
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Junior Member |
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Hello,
I was trying to use IDL curvefit function in order to obtain the
fitting parameters for a non-linear equation. This equation needs a
fixed parameter to be read from an external file, so I wrote a
program that read x,y and this parameter from a file, then it call
the curvefit function (I modified it in order to read this extra
parameter) with the corresponding function_name (where is my
equation, which uses this fixed parameter).
The problem is that Im using the no-weighting form (because Im
fitting one model results to another theoretical equation) and I
obtained nonsense values for the standard deviations on the fitted
coefficients (sigma). I read something about this, and I tried with
the mpcurvefit function too, but I didn't know how to read the
external fixed parameter from the mpcurvefit function (I didnt know
modify it in this case)
Has anybody a solution? Has anybody an alternative program?
--
_____________________________________________________
Raquel Niclòs Corts
Thermodynamics Department
Faculty of Physics
University of Valencia
50 Dr. Moliner
46100 Burjassot (València)
E-mail:Raquel.Niclos@uv.es
Tel: +34 9635 43121
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