[R-sig-Geo] Differences of variogram parameters fitted by gstat and automap

[K Z]

Dear all,

I am currently fitting variograms using both the "autofitVariogram" fuction in the "automap" package and the "fit.variogram" function in the "gstat" package. I used "autofitVariogram" to fit variograms at first, and then I used estimated parameters as the input of the "fit.variogram" function. However, I found the estimated parameters are largely different.  For example, the estimated parameters by the "autofitVariogram" function are

$var_model
  model psill range kappa
1   Nug  2.47     0     0
2   Ste  1.41  2506    10

the estimated parameters by the "fit.variogram" function are:
  model psill range kappa
1   Nug  0.74     0     0
2   Ste  3.03  1269    10

I tried the "exponential" model structure, and got similar results. I understand I probably cannot exactly same results, but I expect I can get similar results. Any suggestion?

I appreciate your response and best regards,
Kai


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