

   LLooggiiccaall VVeeccttoorrss

        TRUE
        FALSE
        T; F

        logical(length = 0)
        as.logical(x)
        is.logical(x)

   DDeessccrriippttiioonn::

        `TRUE' and `FALSE' are part of the R language, where
        `T' and `F' are global variables set to these.  All
        four are `logical(1)' vectors.

        `logical' creates a logical vector of the specified
        length.  Each element of the vector is equal to
        `FALSE'.

        `as.logical' attempts to coerce its argument to be of
        logical type.

        `is.logical' returns `TRUE' or `FALSE' depending on
        whether its argument is of logical type or not.

