[R-sig-Geo] nugget in variogram
edzer.pebesma at uni-muenster.de
Wed Dec 15 07:45:42 CET 2010
> vgm(1, "Exp", 300)
model psill range
1 Exp 1 300
> vgm(1, "Exp", 300, 0)
model psill range
1 Nug 0 0
2 Exp 1 300
are definitions of exactly the same variogram, with zero nugget --
passing either to krige() will yield identical results. If they are
passed to fit.variogram, in the first case no nugget will be fitted, but
in the second case a (zero or positive) nugget will be fitted.
On 12/14/2010 06:09 PM, Piero Campalani wrote:
> Of course, I forgot actually to say I'm using the gstat package, and its
> variogram and vgm functions.
> On 14 December 2010 14:42, kapo coulibaly <kmcoulib at gmail.com> wrote:
>> Which packages and which commands are you using? A little bit of background
>> on how you did it would help.
>> On Tue, Dec 14, 2010 at 4:42 AM, piero campa <piero.campa at gmail.com>wrote:
>>> I am trying to fit my first variograms.
>>> I'm however noticing some weird behaviour I cannot explain.
>>> I'm a 100% newbie.
>>> - without setting a nugget element (so that it should be implicitly 0,
>>> it? In fact the resulting variogram has 0 nugget), the psill and range of
>>> the fitted variogram don't change on different psill inputs.
>>> - If I explicitly set a nugget to 0, then actually the nugget is no more
>>> but higher.
>>> - I tried also setting the fit.sills booleans to TRUE or FALSE to see what
>>> would change, but the output does not really care about it.
>>> Does someone have any hint about this?
>>> Thank you.
>>> View this message in context:
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