_A_r_i_t_h_m_e_t_i_c _M_e_a_n
	
	     mean(x, trim=0, na.rm=FALSE)
	
	_A_r_g_u_m_e_n_t_s:
	
	           x : a numeric vector containing the values whose
	               mean is to be computed.
	
	        trim : the fraction (0 to 0.5) of observations to be
	               trimmed from each end of x before the mean is
	               computed.
	
	       na.rm : a logical value indicating whether NA values
	               should be stripped before the computation
	               proceeds.
	
	_D_e_s_c_r_i_p_t_i_o_n:
	
	     If trim is zero (the default), the arithmetic mean of
	     the values in x is computed.  If trim is non-zero, a
	     symmetrically trimmed mean is computed with a fraction
	     of trim observations deleted from each end before the
	     mean is computed.
	
	     Missing values are ignored.
	
	_S_e_e _A_l_s_o:
	
	     weighted.mean
	
	_E_x_a_m_p_l_e_s:
	
	     xm <- mean(x)