Note on variogram fitting with polynomial degree

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degree is not listed as a parameter in ?variogram, and is ignored,
regrettably silently, but this is how R often works when there's a ...
in the argument list.

The function that accepts degree is ?gstat, and I tried:

variogram(gstat(NULL, "lzinc", log(zinc)~1, meuse, degree=2))

and that gives a nice error message that degree is not supported by
variogram().

I understand this is somewhat confusing. Do you think we should modify
the book or the documentation of some function?

Dear all,

I read in ASDAR: "Residual variograms are calculated by default
when a more complex model for the trend is used..."

However, I noticed that when using fit.variogram in gstat with an 
additional option: degree=2, but keeping the formula as an
intercept only, does not account for the higher degree of
complexity in the model. I suspect this is not the intended
behavior. To honour a dependence structure (polyn degree) in my
observations I need to state the dependence explicitly in the
formula.

Best regards,

Caspar

data(meuse) coordinates(meuse) <- c("x", "y") 
v<-variogram(log(zinc)~1,meuse) print(v) 
vs<-variogram(log(zinc)~1,meuse,degree=2) print(vs) 
vt<-variogram(log(zinc)~x*y+I(x^2)+I(y^2),meuse) print(vt)

PS: x86_64-w64-mingw32/x64 (64-bit) R version 3.0.1 (2013-05-16) 
gstat_1.0-16

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Edzer Pebesma
Institute for Geoinformatics (ifgi), University of M?nster
Heisenbergstra?e 2, 48149 M?nster, Germany. Phone: +49 251
83 33081, Fax: +49 251 8339763 http://ifgi.uni-muenster.de
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