询问下一个matlab求一阶导数的问题
 

f={[theta*(1-d)/(theta*d-d)+1]*w-c}*a*{a*(1+b)/[2*h*(theta-1)]}^(b/1-b)*[(theta-1)*d/theta]^[theta /(1-b)]*w^[(1-b)/(b- theta)]

针对上面的函数对d求一阶导数，我是用diff函数来实现。但是matlab的提示为

??? Error using ==> sym.sym
Conversion to 'sym' from 'cell' is not possible.

Error in ==> sym.mtimes at 8
A = sym(A);

补充：之前使用syms定义变量。对其他稍简单的函数适过：没有问题的。

有经验的朋友进来解答。

回复: 询问下一个matlab求一阶导数的问题
 

对函数f的书写不合matlab语法----此处花括弧、方括弧用错。

回复: 询问下一个matlab求一阶导数的问题
 

>>syms theta a b c d w h;
>>f=( ( theta*(1-d)/(theta*d-d)+1 ) *w-c )*a*( a*(1+b)/ ( 2*h*(theta-1) ) )^(b/1-b)* ( (theta-1)*d/theta ) ^ (theta /(1-b) ) *w^ ( (1-b)/(b- theta) );
>>pretty(f);
>>foverd = diff(f,d)
>>foverd=
(a*w*(theta/(d - d*theta) + (theta*(d - 1)*(theta - 1))/(d - d*theta)^2))/(w^((b - 1)/(b - theta))*((d*(theta - 1))/theta)^(theta/(b - 1))) + (a*(theta - 1)*(c - w*((theta*(d - 1))/(d - d*theta) + 1)))/(w^((b - 1)/(b - theta))*(b - 1)*((d*(theta - 1))/theta)^(theta/(b - 1) + 1))
注：计算有点儿慢。

回复: 询问下一个matlab求一阶导数的问题
 

>>pretty(foverd)

/ theta theta (d - 1) (theta - 1) \
a w | ----------- + ------------------------- |
| d - d theta 2 |
\ (d - d theta) /
----------------------------------------------- +
theta
b - 1 -----
--------- b - 1
b - theta / d (theta - 1) \
w | ------------- |
\ theta /

/ / theta (d - 1) \ \
a (theta - 1) | c - w | ------------- + 1 | |
\ \ d - d theta / /
---------------------------------------------
theta
b - 1 ----- + 1
--------- b - 1
b - theta / d (theta - 1) \
w (b - 1) | ------------- |
\ theta /