

   VVaarriiooggrraamm

        vgram(loc, y, lon.lat=F)

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

        loc: Matrix where each row is the coordinates of an
             observed point of the field

          y: Value of the field at locations

    lon.lat: If true, locations are assumed to be longitudes
             and latitudes and distances found are great circle
             distances. Default is false.

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

        Object of class vgram.  This is list with components d
        the pairwise distances , vgram the value of the vari-
        ogram and loc the locations.

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

        See any standard reference on spatial statistics. For
        example Cressie Spatial Statistics

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

        # compute variogram for the Chicago ozone field
        vgram( ozone$x, ozone$y, lon.lat=T)-> out
        plot( out$d, out$vgram, xlab="Distance", ylab="Squared differences")

