

   SSiiggnn FFuunnccttiioonn

        sign(x)

   AArrgguummeennttss::

          x: a numeric vector

   DDeessccrriippttiioonn::

        `sign' returns a vector with the signs of the corre-
        sponding elements of `x' (the sign of a real number is
        1, 0, or -1 if the number is positive, zero, or nega-
        tive, respectively).

        Note that `sign' does not operate on complex vectors.

   SSeeee AAllssoo::

        `abs'

   EExxaammpplleess::

        sign(pi) # == 1
        sign(-2:3)# -1 -1 0 1 1 1

