Plot multiple subintervals in one figure

Question

Joakim Karlsson 2017-11-9

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此问题的直接链接

https://ww2.mathworks.cn/matlabcentral/answers/366136-plot-multiple-subintervals-in-one-figure

评论： Rik 2017-11-11

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??

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Rik 2017-11-9

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

Joakim Karlsson 2017-11-10

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

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Answer 1

Mischa Kim 2017-11-10

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此回答的直接链接

https://ww2.mathworks.cn/matlabcentral/answers/366136-plot-multiple-subintervals-in-one-figure#answer_290337

编辑：Mischa Kim 2017-11-10

在 MATLAB Online 中打开

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

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Joakim Karlsson 2017-11-10

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 2017-11-11

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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