Trying to plot summation based sine signal

I am generating a random signal based on summation.

Here is the code:

clear all

clc

format long

syms x u

L = 2*pi;

s = rand;

si = L*s;

G5_6 = gamma(5/6); G1_3 = gamma(1/3); k_di = 10000/35;

C = (55/9)*(G5_6/(sqrt(pi)*G1_3));

sigma = 2; ke = 5; l = (2*pi)/5;

n = 1; N=10; u = 0; eta = l/(10^4);

nke = n/ke; k_eta = (2*pi)/eta;

sigma_n = k_eta/10; a_n = 0;

for i = n:N

E_vk = C*((sigma^2)/ke)*((nke)^4)/((1+nke^2)^(17/6));

E_n = E_vk*exp((-(n-k_di)^2)/(sigma_n^2));

a_n = ((2*E_n)^(1/2)) + a_n;

u = (a_n*sin(n*x+si) + u);

end

u

Now, I want to plot u on y-axis against x on x-axis that goes from 0 to 10*pi

I have tried a few things but nothing works, please help

Answer 1

[Torsten]

syms x  
L = 2*pi;
s = rand;
si = L*s;
G5_6 = gamma(5/6); G1_3 = gamma(1/3); k_di = 10000/35;
C = (55/9)*(G5_6/(sqrt(pi)*G1_3));
sigma = 2; ke = 5; l = (2*pi)/5;
n = 1; N=10; u = 0; eta = l/(10^4);
nke = n/ke; k_eta = (2*pi)/eta;
sigma_n = k_eta/10; a_n = 0;
for i = n:N
    E_vk = C*((sigma^2)/ke)*((nke)^4)/((1+nke^2)^(17/6));
    E_n = E_vk*exp((-(n-k_di)^2)/(sigma_n^2));
    a_n = ((2*E_n)^(1/2)) + a_n;
    u = (a_n*sin(n*x+si) + u);    
end
xnum = linspace(0,10*pi,1000);
unum = subs(u,x,xnum);
plot(xnum,unum)

[Saim]

Thanks