

   DDoouubbllee PPrreecciissiioonn VVeeccttoorrss

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

   VVaalluuee::

        `double' creates a double precision vector of the spec-
        ified length.  The elements of the vector are all equal
        to `0'.

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

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

   NNoottee::

        R has no single precision data type.  All real numbers
        are stored in double precision format.

   SSeeee AAllssoo::

        `integer'.

   EExxaammpplleess::

        is.double(1)
        all(double(3) == 0)

