About partial derivative using Matlab

I want to get the partial derivative of a complex function, so I used Matlab and writed the following codes:

syms x1 x2 x3 x4 x5 x6 x7 x8 x9 x10 x11 x12 x13 x14 x15 x16 x17 x18 x19 x20

y(1)=exp(-(u(1)-x1).^2/(2*x2^2));

y(2)=exp(-(u(1)-x3).^2/(2*x4^2));

y(3)=exp(-(u(1)-x5).^2/(2*x6^2));

y(4)=exp(-(u(1)-x7).^2/(2*x8^2));

y(5)=exp(-(u(1)-x9).^2/(2*x10^2));

y(6)=exp(-(u(2)-x11).^2/(2*x12^2));

y(7)=exp(-(u(2)-x13).^2/(2*x14^2));

y(8)=exp(-(u(2)-x15).^2/(2*x16^2));

y(9)=exp(-(u(2)-x17).^2/(2*x18^2));

y(10)=exp(-(u(2)-x19).^2/(2*x20^2));

z(1)=y(1)*y(6);z(2)=y(1)*y(7);z(3)=y(1)*y(8);z(4)=y(1)*y(9);z(5)=y(1)*y(10);

z(6)=y(2)*y(6);z(7)=y(2)*y(7);z(8)=y(2)*y(8);z(9)=y(2)*y(9);z(10)=y(2)*y(10);

z(11)=y(3)*y(6);z(12)=y(3)*y(7);z(13)=y(3)*y(8);z(14)=y(3)*y(9);z(15)=y(3)*y(10);

z(16)=y(4)*y(6);z(17)=y(4)*y(7);z(18)=y(4)*y(8);z(19)=y(4)*y(9);z(20)=y(4)*y(10);

z(21)=y(5)*y(6);z(22)=y(5)*y(7);z(23)=y(5)*y(8);z(24)=y(5)*y(9);z(25)=y(5)*y(10);

m=(2*z(16)+2*z(21)+2*z(22)+z(11)+z(17)+z(23)+z(24)-z(3)-z(9)-2*z(4)-2*z(5)-2*z(10))/(z(1)+z(2)+z(3)+z(4)+z(5)+z(6)+z(7)+z(8)+z(9)+z(10)+z(11)+z(12)+z(13)+z(14)+z(15)+z(16)+z(17)+z(18)+z(19)+z(20)+z(21)+z(22)+z(23)+z(24)+z(25));

mx1=diff('m','x1')

but there are the errors:

??? Error using ==> mupadmex

Error in MuPAD command: Index exceeds matrix dimensions.

Error in ==> sym.sym>sym.subsref at 1381

   B = mupadmex('symobj::subsref',A.s,inds{:});

How can I solve the problem? Thanks

[Walter Roberson]

Have you tried

diff(m, x1)

?

Answer 1

[autshy]

this problem was solved now..