波德圖
the Nichols plots displays formula_3 versus formula_4. Loci of constant formula_5 and formula_6 are overlaid to allow the designer to obtain the closed loop transfer function directly from the open loop transfer function. Thus, the frequency formula_7 is the parameter along the curve. This plot may be compared to the Bode plot in which the two inter-related graphs - formula_3 versus formula_9 and formula_4 versus formula_9) - are plotted.