_D_o_u_b_l_e _P_r_e_c_i_s_i_o_n _V_e_c_t_o_r_s
	
	     double(n=0)
	
	     as.double(x)
	     is.double(x)
	
	_V_a_l_u_e:
	
	     This function 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 dou-
	     ble 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)