

   MMaattrriixx CCrroosssspprroodduucctt

        crossprod(x, y=x)

   DDeessccrriippttiioonn::

        Given matrices `x' and `y' as arguments, `t' returns
        their matrix cross-product.  This is formally equiva-
        lent to, but faster than, the call `t(x) %*% y'.

   SSeeee AAllssoo::

        `outer'

   EExxaammpplleess::

        crossprod(1:4)# = sum(1 + 2^2 + 3^2 + 4^2)

