What wrong with the code

I have an assignment question which involve matlab to plot the above graph and below are the code I used.

y=linspace(0,6,10);

x=linspace(0,11,10);

[X,Y]=meshgrid(x,y);

U=(400/pi)*symsum((sin((n*pi*X)/11).*sinh(n*pi*Y/11))/(n*sinh((n*pi*6)/11)),n,1,200);

surf(X,Y,U)

and it return the error"Invalid parameter/value pair arguments"

I'm not sure why it display such error and i check by using simpler function like U=X.*Y, it able to plot the graph, so I cannot identify where the error in my original equation as below.

U=(400/pi)*symsum((sin((n*pi*X)/11).*sinh(n*pi*Y/11))/(n*sinh((n*pi*6)/11)),n,1,200);

but command like plot3(X,Y,U) is working .

Answer 1

[chris crowley]

Your superfluous use of parentheses made it hard to spot, but you have the wrong number of them in your calculation of U. Take a closer look.

Also, you could do this without needing the symbolic toolbox like this:

y=linspace(0,6,10);
x=linspace(0,11,10);
[X,Y]=meshgrid(x,y);
U = zeros(size(X));
for n = 1:2:200
    U = U + sin(n*pi*X/11).*sinh(n*pi*Y/11)/ (n*sinh(n*pi*6/11));
end
U = (400/pi)*U;

surf(X,Y,U)

[kt chua]

Thanks for spoting my mistake. The for loop command indeed cleaner and much easier to perform the function for Odd value of n.