

_D_o_u_b_l_e _P_r_e_c_i_s_i_o_n _V_e_c_t_o_r_s

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

_V_a_l_u_e:

     `double' creates a double precision vector of the
     specified 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.

_N_o_t_e:

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

_S_e_e _A_l_s_o:

     `integer'.

_E_x_a_m_p_l_e_s:

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

