

_L_o_g_i_c_a_l _V_e_c_t_o_r_s

     TRUE
     FALSE
     T; F

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

_D_e_s_c_r_i_p_t_i_o_n:

     `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.

