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Plot multiple subintervals in one figure

Joakim Karlsson さんによって質問されました 2017 年 11 月 9 日
最新アクティビティ Rik
さんによって コメントされました 2017 年 11 月 11 日
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??

  2 件のコメント

Rik
on 9 Nov 2017
You did run the plot command another time after the hold on?
Yes I did but the script just computed the first thing again. So it didn't really change anything.

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1 件の回答

Mischa Kim
Answer by Mischa Kim
on 10 Nov 2017
Edited by Mischa Kim
on 10 Nov 2017
 Accepted Answer

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

  4 件のコメント

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.
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
on 11 Nov 2017
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)

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