# Matlab plot3 not giving a 3D plot

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Jonas Freiheit on 14 May 2022
Answered: Steven Lord on 15 May 2022
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
Jonas Freiheit on 15 May 2022
Thanks Cris

Steven Lord on 15 May 2022
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 