

   VVaarriiooggrraamm EEssttiimmaattoorr

        est.variogram(point.obj, pairs.obj, v1, v2=v1)

   AArrgguummeennttss::

   point.obj: a point object generated by `point()'

   pairs.obj: a pairs object generated by `pairs()'

         v1: a variable to calculate semivariogram for

         v2: an optional variable name, if entered cross vari
             ograms will be created between `v1' and `v2'

   DDeessccrriippttiioonn::

        Calculate empirical variogram estimates.

        An object of class `variogram' contains empirical vari
        ogram estimates generated from a point object and a
        pairs object. A variogram object is stored as a data
        frame containing six columns: `lags', `bins', `clas
        sic', `robust', `med', and `n'. The length of each vec
        tor is equal to the number of lags in the pairs object
        used to create the variogram object, say l. The `lags'
        vector contains the lag numbers for each lag, beginning
        with one (1) and going to the number of lags (l). The
        `bins' vector contains the spatial midpoint of each
        lag. The `classic', `robust', and `med' vectors contain
        the classical, robust, and median variogram estimates
        for each lag, respectively (see Cressie, 1993, p. 75).
        The `n' vector contains the number of pairs of points
        in each lag.

   VVaalluuee::

        A variogram object:

       lags: vector of lag identifiers

       bins: vector of midpoints of each lag

    classic: vector of classic variogram estimates for each lag

     robust: vector of robust variogram estimates for each lag

        med: vector of median variogram estimates for each lag

          n: vector of the number of pairs in each lag

   RReeffeerreenncceess::

        http://www.gis.iastate.edu/SGeoStat/homepage.html

   SSeeee AAllssoo::

        `point', `pairs'

   EExxaammpplleess::

        maas.v<-est.variogram(maas.pts,maas.pairs,'zinc')

