S-News readers,
I'm interested in learning about the algorithms used to compute
empirical or sample semivariograms. I have S+SpatialStats, for example,
so I have the means for calculating empirical semivariograms. I also
understand the basic formula
gamma(h) = 0.5*N(h)*sum(Zi - Zj)^2
used for estimating the semivariogram where h = i - j is the Euclidean
distance or "lag" and N(h) is the number of data pairs. So my interest
is in learning about how to do these calculations in S-PLUS so that I
can experiment with other approaches for estimating these kinds of
statistics. I am assuming that there are some relatively efficient ways
to do these calculations using vectors and matrices. If anyone has
written code to do this in S-PLUS that they wouldn't mind sharing, I
would be grateful.
Thanks.
-Paul
Paul Schwarz
Cornell University
Department of Natural Resources
Fernow Hall
Ithaca, New York 14853-3001
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