

   SSeeqquueennccee GGeenneerraattiioonn

        from:to
        seq(from, to)
        seq(from, to, by=)
        seq(from, to, length=)
        seq(along)

   DDeessccrriippttiioonn::

        The `:' and the first `seq(.)' form above generate the
        sequence `from, from+1', ..., `to'.  `seq' is a generic
        function.

        The second, `from, from+by', ..., `to'.  The third gen-
        erates a sequence of `length' equally spaced values
        from `from' to `to'.  The last generates the sequence
        `1, 2', ..., `length(along)'.

        If `from' and `to' are factors of the same length, the
        ``cross'' of the two is returned.

   VVaalluuee::

        The result is of `mode' `"integer"' if `from' is
        (numerically equal to an) integer.

   SSeeee AAllssoo::

        `rep', `sequence', `row', `col'.

   EExxaammpplleess::

        1:4
        pi:6 # float
        6:pi # integer

        seq(0,1, length=11)
        seq(1,9, by = 2) # match
        seq(1,9, by = pi)# stay below
        seq(1,6, by = 3)
        seq(1.575, 5.125, by=0.05)

        1:4
        pi:6 # float
        6:pi # integer

        seq(0,1, length=11)
        seq(1,9, by = 2) # match
        seq(1,9, by = pi)# stay below
        seq(1,6, by = 3)
        seq(1.575, 5.125, by=0.05)

        for (x in list(NULL, letters[1:6], list(1,pi)))
          cat("x=",deparse(x),";  seq(along = x):",seq(along = x),"\n")

        f1_ gl(2,3); f1
        f2_ gl(3,2); f2
        f1:f2 # a factor, the ``cross''  f1 x f2

        for (x in list(NULL, letters[1:6], list(1,pi)))
          cat("x=",deparse(x),";  seq(along = x):",seq(along = x),"\n")

        f1_ gl(2,3); f1
        f2_ gl(3,2); f2
        f1:f2 # a factor, the ``cross''  f1 x f2

