

   BBiinn bbiivvaarriiaattee ddaattaa xx

        bin2(x, ab, nbin)

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

          x: (input matrix with 2 columns) data sample

         ab: (input 2 x 2 matrix) rows 1 and 2 contain x and y
             axis bin intervals, respectively.  If not speci-
             fied, the ranges are stretched by 5% at each end
             for each dimension.

       nbin: (input vector of length 2) number of bins along x
             and y axes. Default is 20 by 20.

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

        `bin2' returns a list including the bivariate bin
        matrix and the number of points outside the ab rectan-
        gle.

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

        `ash2'

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

        x <- matrix( rnorm(200), 100 , 2)       # bivariate normal n=100
        ab <- matrix( c(-5,-5,5,5), 2, 2)       # interval [-5,5) x [-5,5)
        nbin <- c( 20, 20)                      # 400 bins
        bins <- bin2(x, ab, nbin)               # bin counts,ab,nskip

