[R-sig-Geo] Custom variogram models in gstat

[Edzer Pebesma]

Alessandro, you have two options:

First, gstat is open source, is written modular, so it is fairly
straightforward to add variogram models, but this has to be done at the
level of C code. src/vario_fn.c and src/vario_fn.h are the files to look
at; search for 'bess' and add yours. If you do, please consider
contributing your modifications back to us.

Second option is to pre-calculate values of your model in a table, and
provide the to gstat as a set of values to work with, see an example in:

https://r-forge.r-project.org/scm/viewvc.php/pkg/tests/covtable.R?view=markup&root=gstat

Hth,
--
Edzer

On 03/18/2013 12:52 PM, Alessandro Samuel Rosa wrote:
> 
> Hi, is it possible to use 
> custom variogram models in gstat? I have a data set with a hole effect. 
> I've been searching the literature and found out that the Bessel model (J type) is the most appropriate (see Webster and Oliver, 2007). gstat has Bessel K. Does anyone knows a solution?
>  
> Alessandro Samuel-Rosa
> Postgraduate Course in Agronomy - Soil Science
> Federal Rural University of Rio de Janeiro
> Seropédica, Rio de Janeiro, Brazil
> soil-scientist.net
> 
> "If we had obeyed our elders, the high priests in our field of science when we were young, if we had relied on them to guide our research, then we should still be grappling with the legacy of John Stuart Mill and Aristotle. No; it is for the young to have their ideas, and for us older ones to allow those ideas to bubble to the surface. We may modify them, channel them, challenge them,  criticize them; but at all events we should encourage them. The young and their ideas are our future." Richard Webster (1994)
> 
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> 
> 
> 
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-- 
Edzer Pebesma
Institute for Geoinformatics (ifgi), University of Münster
Weseler Straße 253, 48151 Münster, Germany. Phone: +49 251
8333081, Fax: +49 251 8339763  http://ifgi.uni-muenster.de
http://www.52north.org/geostatistics      e.pebesma at wwu.de