阶数	Cobb-Douglas函数
n = 0	$f (x) = e^{a} x_{1}^{b} x_{2}^{c} x_{3}^{1 - b - c}$	(3)
n = 1	$f (x) = e^{a t + b} x_{1}^{c} x_{2}^{d} x_{3}^{1 - c - d}$	(4)
n = 2	$f (x) = e^{a t^{2} + b t + c} x_{1}^{d} x_{2}^{e} x_{3}^{1 - d - e}$	(5)
n = 3	$f (x) = e^{a t^{3} + b t^{2} + c t + d} x_{1}^{e} x_{2}^{f} x_{3}^{1 - e - f}$	(6)
n = 4	$f (x) = e^{a t^{4} + b t^{3} + c t^{2} + d t + e} x_{1}^{f} x_{2}^{g} x_{3}^{1 - f - g}$	(7)
n = 5	$f (x) = e^{a t^{5} + b t^{4} + c t^{3} + d t^{2} + e t + f} x_{1}^{g} x_{2}^{h} x_{3}^{1 - g - h}$	(8)