Matlab plot3 not giving a 3D plot

Question

Jonas Freiheit 2022-5-14

0
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此问题的直接链接

https://ww2.mathworks.cn/matlabcentral/answers/1719460-matlab-plot3-not-giving-a-3d-plot

回答： Steven Lord 2022-5-15

Hi all, Sorry I'm a beginner with Matlab and don't understand why my plot3 with 3 inputs is not giving me a 3D representation of 4 bugs travelling on a 3D plane?

Here is my code:

clc, clear, clear all

ti=0;

tf=1000;

tspan= linspace(ti,tf,1000000);

f0 = [0; 0; 0; 1; 2; 0; 1; 0; 3; 0; 2; 3];

[t, f] = ode45(@g, tspan, f0);

%Trajectories are done in 3 coordinates x,y,z

i_1=(f(:,1)); %Trajectory of bug 1

j_1=(f(:,2));

k_1=(f(:,3));

i_2=(f(:,4)); %Trajectory of bug 2

j_2=(f(:,5));

k_2=(f(:,6));

i_3=(f(:,7)); %Trajectory of bug 3

j_3=(f(:,8));

k_3=(f(:,9));

i_4=(f(:,10));

j_4=(f(:,11));

k_4=(f(:,12));

figure

hold on

plot3(i_1, j_1, k_1)

plot3(i_2, j_2, k_2)

plot3(i_3, j_3, k_3)

plot3(i_4, j_4, k_4)

title('test')

xlabel('x')

ylabel('y')

zlabel('z')

function dxdt = g(t,f)

a = sqrt((f(2)-f(1))^2 + (f(6)-f(5))^2 + (f(10)-f(9))^2);

b = sqrt((f(3)-f(2))^2 + (f(7)-f(6))^2 + (f(11)-f(10))^2);

c = sqrt((f(4)-f(3))^2 + (f(8)-f(7))^2 + (f(12)-f(11))^2);

d = sqrt((f(1)-f(4))^2 + (f(5)-f(8))^2 + (f(9) -f(12))^2);

dxdt = [ ...

(f(2) - f(1)) / a;

(f(6) - f(5)) / a;

(f(10) - f(9)) / a;

(f(3) - f(2)) / b;

(f(7) - f(6)) / b;

(f(11) - f(10)) / b;

(f(4) - f(3)) / c;

(f(8) - f(7)) / c;

(f(12) - f(11)) / c;

(f(1) - f(4)) / d;

(f(5) - f(8)) / d;

(f(9) - f(12)) / d];

end

Thank you

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Cris LaPierre 2022-5-15

在 MATLAB Online 中打开

I suggest one minor change to Torsten's code:

figure
plot3(i_1, j_1, k_1)
hold on
plot3(i_2, j_2, k_2)
plot3(i_3, j_3, k_3)
plot3(i_4, j_4, k_4)
hold off
title('test')
xlabel('x')
ylabel('y')
zlabel('z')

Use the Axes Toolbar to rotate the plot. See here for how to access it in a live script:

https://www.mathworks.com/help/matlab/matlab_prog/modify-output-figures.html

Jonas Freiheit 2022-5-15

Thanks Cris

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Answer 1

Steven Lord 2022-5-15

1
链接

此回答的直接链接

https://ww2.mathworks.cn/matlabcentral/answers/1719460-matlab-plot3-not-giving-a-3d-plot#answer_964180

在 MATLAB Online 中打开

Since no axes existed when you called hold on, MATLAB created one using the default 2-D view and "locked" that axes property in place. Locking certain axes properties in place, so MATLAB doesn't automatically change them, is one of the main purposes of the hold function. So when you called plot3 it would have changed the view but effectively hold said "You can't do that."

The code @Cris LaPierre posted called plot3 before hold so the axes that was "locked" used the 3-D view. You could also call view to manually change the view. hold prevents MATLAB from automatically changing properties, but it doesn't prevent you the user from manually changing them.

figure

hold on

plot3(1:10, 1:10, 1:10) % Uses the 2-D view

view(3) % Manually change it to be in 3-D view