Graphs Not Showing Up

clear all;
close all;
clc;

x = linspace(0,2);

for t = [0 1 2 3 4]
    n = 2;
    Cn = 32;
    Dn = 0;
    u2 = (sin((n*pi*x)/2))*(Cn*cos(5*n*pi*t)+Dn*sin(5*n*pi*t));

      n = 4;
      Cn = 32;
      Dn = 0;
      u4 = (sin((n*pi*x)/2))*(Cn*cos(5*n*pi*t)+Dn*sin(5*n*pi*t));

      n = 5;
      Cn = 32;
      Dn = 0;
      u5 = (sin((n*pi*x)/2))*(Cn*cos(5*n*pi*t)+Dn*sin(5*n*pi*t));

      n = 6;
      Cn = 32;
      Dn = 0;
      u6 = (sin((n*pi*x)/2))*(Cn*cos(5*n*pi*t)+Dn*sin(5*n*pi*t));

      n = 12;
      Cn = 32;
      Dn = 0;
      u12 = (sin((n*pi*x)/2))*(Cn*cos(5*n*pi*t)+Dn*sin(5*n*pi*t));

      u = u2 + u4 + u5 + u6 + u12
      plot(x,u)
      hold on
      grid on
      legend('0', '1', '2', '3', '4')
      title('u(x,t)')
      xlabel('x')
      ylabel('u(x,t)')
  end

This is my code to plot multiple graphs for a PDE, however no graphs actually show up for t = 0, 1 and 2. What's weird though is when I just have

t = 0

the plot comes up. Would anyone be able to help me as to why it is not working when trying to plot for multiple t?

Answer 1

[KSSV]

It is showing up for all the time steps....But it is taking same values. so you are able to see only few curves. Check the below code:

clear all;
close all;
clc;
x = linspace(0,2);
mark = {'*r','.k','Og','dc','sm'} ;
T = [0 1 2 3 4] ;
for i = 1:length(T)
    t = T(i) ;
    n = 2;
    Cn = 32;
    Dn = 0;
    u2 = (sin((n*pi*x)/2))*(Cn*cos(5*n*pi*t)+Dn*sin(5*n*pi*t));
    n = 4;
    Cn = 32;
    Dn = 0;
    u4 = (sin((n*pi*x)/2))*(Cn*cos(5*n*pi*t)+Dn*sin(5*n*pi*t));
    n = 5;
    Cn = 32;
    Dn = 0;
    u5 = (sin((n*pi*x)/2))*(Cn*cos(5*n*pi*t)+Dn*sin(5*n*pi*t));
    n = 6;
    Cn = 32;
    Dn = 0;
    u6 = (sin((n*pi*x)/2))*(Cn*cos(5*n*pi*t)+Dn*sin(5*n*pi*t));
    n = 12;
    Cn = 32;
    Dn = 0;
    u12 = (sin((n*pi*x)/2))*(Cn*cos(5*n*pi*t)+Dn*sin(5*n*pi*t));
    u = u2 + u4 + u5 + u6 + u12 ;
    plot(x,u,mark{i})
    hold on
    grid on
    legend('0', '1', '2', '3', '4')
    title('u(x,t)')
    xlabel('x')
    ylabel('u(x,t)')
end

Answer 2

[Massimo Zanetti]

You just see the last two ('3' and '4') because the values are the same, so curve are superimposed and you just see the last one which is printed. A comment about your code, put legend and labels outside the for loop:

for t = [0 1 2 3 4]
    %...... your code
      plot(x,u)
      hold on
end
grid on
legend('0', '1', '2', '3', '4')
title('u(x,t)')
xlabel('x')
ylabel('u(x,t)')
hold off

and add hold off