What commands should I add to get these flux lines?

%a and b are the dimensions of the trough.

clear all;

close all;

clc;

P=[];

Vo=100.0;

a=1.0;

b=2.*a;

x=b/4;

y=3.*a/4;

c=4.*Vo/pi

sum=0.0;

for k=1:10

      n=2*k-1

      a1=sin(n*pi*x/b);

      a2=sinh(n*pi*y/b);

      a3=n*sinh(n*pi*a/b);

      sum=sum+c*a1*a2/a3;

      P=[n, sum]

end

diary test.out

P

diary off

[Star Strider]

How did the paper you copied that plot from calculate them?

I cannot follow your code.

[merey]

this is the starting point:

here is the general equation and then the solution of the problem,

[merey]

and this is the problem from the beginning: