Plotting results of for loop on one graph

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Kelly Berry
Kelly Berry 2015-9-17
评论： faith 2023-11-3
Hi, I am relatively unexperienced with MATLAB, so bear with me! I created a for loop where two of the values in my matrix are functions of r, and then further operations are performed with each iteration of the matrix. The values are generated but then when I try to graph them, I get either an error or no graph. Here's my code:
for r=0:0.001:1.1;
M=[-1*(r.^2)+1.3 -0.3;-0.3, -0.3*(r.^2)+0.3];
f=[1;0];
z_1=M\f;
plot(r,z_1)
end
Thank you in advance!
**As an added comment, if I try to express z_1 as z_1(r), or do this operation without the for loop, I get the error "Subscript indices must either be real positive integers or logicals" and I also don't know how to fix that...

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采纳的回答

Jon
Jon 2015-9-17
编辑：Jon 2015-9-17
Replace your plot(r,z_1) with this:
plot(r,z_1,'.'); hold on
If you don't turn the "hold" to "on" then the figure is overwritten with each iteration.
You can also achieve this by adding these commands before the loop:
figure; hold on
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faith
faith 2023-11-3
can we use the same solution to plot more than one graph in each iteration of the loop? for example, I want to sketch the graph of two circles, and one line further. I, also want to shrink one of the circles in each iteration of a loop. thanks in advance

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更多回答（2 个）

Jae Song
Jae Song 2015-9-17
The z_1 matrix variable needs to have index; Please see the following code
x = 0:0.001:1.1;
s = size(x,2); %: get the array size
for i=1:s
r = x(i);
M=[-1*(r.^2)+1.3 -0.3;-0.3, -0.3*(r.^2)+0.3];
f=[1;0];
z_1(:,i)=M\f;
end
figure(1); plot(x,z_1(1,:));
figure(2); plot(x,z_1(2,:));
  2 个评论
Kelly Berry
Kelly Berry 2015-9-17
Thanks Jae!! I used a combination of your answer and Jon's, and I finally got it to work! I definitely appreciate your help!
Nasir Mehmood
Nasir Mehmood 2020-9-25
Hello dear Jae Song! I'm new to Matlab.
When I change
x = 0:0.001:1.1;
to
x = 0:0.01:1.1;
no plot is obtained. How to handle this issue?
Also can you describe a little about these lines:
z_1(:,i)=M\f;
and
figure(1); plot(x,z_1(1,:));

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Hansa Prasad
Hansa Prasad 2019-2-15
T0=24;
m0=1;
eta=4.2;
T(1)=T0;
m(1)=m0;
C=216;
R=2;
Ta=26;
P=2;
Ts=21;
for t=1:300:1;
T(t+1)=(-1/(C*R))*(T(t)-Ta+m(t)*R*P*eta)+T(t);
plot(t,T(t))
end

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