Plot multiple subintervals in one figure

Hello all. Probably quite an easy problem but I am stuck.

f=@(t,u)-u+sin(5*t)+cos(2*t);
a=0; b=5; ua=2; % begynnelsevillkor
t=linspace(a,b,15); u=linspace(-2,2,15);
riktningsfaelt(f,t,u);
N=10; h=(b-a)/N; %steglängd
T=linspace(a,b,N+1); U=zeros(size(T)); 
U(2)=ua; %enligt begynnelsevillkor
for n=1:N
U(n+1)=U(n)+h*f(T(n),U(n)); % Eulers metod
end
plot(T,U)

So what I want to do is plot but with different N values in the same figure. I have tried "hold on" then set a new N value but it doesn't work. Lets say I want to plot N=10 and N=100 in the same figure, how do I do that??

[Rik]

You did run the plot command another time after the hold on?

[Joakim Karlsson]

Yes I did but the script just computed the first thing again. So it didn't really change anything.

Answer 1

[Mischa Kim]

Joakim, is this what you had in mind?

f=@(t,u)-u+sin(5*t)+cos(2*t);
a=0; b=5; ua=2; % begynnelsevillkor
t=linspace(a,b,15); u=linspace(-2,2,15);
% riktningsfaelt(f,t,u);
for N = 10:10:100
    h=(b-a)/N; %steglängd
    T=linspace(a,b,N+1);
    U=zeros(size(T));
    U(2)=ua; %enligt begynnelsevillkor
    for n=1:N
        U(n+1)=U(n)+h*f(T(n),U(n)); % Eulers metod
    end
    plot(T,U)
    hold on
end

[Joakim Karlsson]

Hmm not really. I want to set N=10,100,1000 and plot these three different with colors. Since a higher N value smoothes the curve i want to show the Difference what happens when you have a different N value

[Mischa Kim]

Simple enough. Replace the for command by

 for N = [10,100,1000]

The code in my first answer above creates essentially the same graph, just with 10 plots vs 3.

[Joakim Karlsson]

Yeah this works very well actually. Now I'd just like to set my own colours if that is possible since its hard to look at it when one is yellow and one is orange haha.

[Rik]

Save the handles to the line objects (output of plot function) and you can set the color. (or just use a cell array with the color string inside the for-loop)