Dear all,
I am working with nlme under S-plus 2000 release 3. I would like to specify
a variance function involving more than one covariate, but not in a
multiplying way (involving varComb in this case).
The variance function I want to use should be featured as follows :
weights = varPower(form = ~ (fitted(.) - covariate))
Pinheiro and Bates (2000) do not give any exemple of this kind.
The adjustment procedure seems to work well, and finally delivers the
following warning :
Warning messages:
"Inf" is a constant object in S: you should choose a different variable
name in: .C("terms_pass1", ...
Is there any connexion with the variance function specified ? Is this
function correct or is ther another way to reach this formulation ?
Any help appreciated ! With many thanks.
JD Bontemps
--
Jean-Daniel BONTEMPS
UMR 1092 Inra-Engref "LERFoB" - équipe Ecologie Forestière
ENGREF - 14, rue Girardet
F-54000 NANCY
tél: (+33) (0)3 83 39 68 75
mél: bontemps@engref.fr
www.nancy.inra.fr/lerfob/
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