
Dear sir,
I spent lot of time to figured it out what causing the difference in result of R/gstat and gslib but didn't get any logical explanation. In my opinion the source of difference is the cutoff and width. 
I would be thankful if you give me the in depth explanation of these two parameters used in gstat or you can suggest me the suitable value i should adopt for my case. In my data set the diagonal is 2771.89 so 1/3 of it is 923.96 i believe this is the default cutoff. but what about width, i don't get the logic of this function? where as in gslib we have to define the limit to what level pairs will be compared and the distance between the pairs and its tolerance. for my case in case of directional semivariogram the distance between is 12m and tolerance 6m and the extent is 923.96m that is i have to define numbers of lag as 923.96/12 ~77 nos. i didn't see the tolerance for lag in gstat, i think this has been done with build in script which incorporates with tol.hor command?? One more querry; is it correct to use same cutoff and width for omnidirectional and directional semivariogram (especially in 45 and 135 directions)?? as the lag in 0 and 90 directions is 12 where as in 45 and 135 is 16.97m.
Though my question seems very basic, hope you find sometime to answer them
Thanking you
Pujan

> Date: Wed, 7 May 2008 18:27:44 +0200
> From: edzer.pebesma@uni-muenster.de
> To: regmi_pujan@hotmail.com
> CC: thierry.onkelinx@inbo.be; r-sig-geo@stat.math.ethz.ch
> Subject: Re: [R-sig-Geo] variogram using gstat
> 
> PUJAN RAJ REGMI wrote:
> >
> > Dear sir,
> > Ya, Now I am comparing the results from gslib and R/gsat. The shape of 
> > variograms exactly overlaps but the position of points varies, I don't 
> > know why? or it is normal! I first checked the result of 
> > omnidirectional variogram but still to have checked for directional 
> > cases. I hope the plot will overlap exactly on these cases too!!
> > Thanking you
> > Pujan
> >  
> Does gslib also compute average distances over the point pairs, or does 
> it give the middle point of the distance bin?
> --
> Edzer

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