# Out of memory error message when attempting to plot in 3D

3 views (last 30 days)
Jonas Freiheit on 13 May 2022
Edited: Jan on 13 May 2022
Hi all,
From my following code as I'm trying to plot the trajectory of 3 bugs in three dimensions I am presented with the folllowing error message:
Out of memory. The likely cause is an infinite recursion within the program.
Error in bugs>g (line 37) dxdt=g(t,f)
From my following 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, tspan)
plot3(i_2, j_2, k_2, tspan)
plot3(i_3, j_3, k_3, tspan)
plot3(i_4, j_4, k_4, tspan)
title('test')
xlabel('x')
ylabel('y')
zlabel('z')
function dxdt = g(t,f)
dxdt=g(t,f)
dxdt=[(f(2)-f(1))/(sqrt((f(2)-f(1))^2+(f(6)-f(5))^2+(f(10)-f(9))^2));
(f(6)-f(5))/(sqrt((f(2)-f(1))^2+(f(6)-f(5))^2+(f(10)-f(9))^2));
(f(10)-f(9))/(sqrt((f(2)-f(1))^2+(f(6)-f(5))^2+(f(10)-f(9))^2));
(f(3)-f(2))/(sqrt((f(3)-f(2))^2+(f(7)-f(6))^2+(f(11)-f(10))^2));
(f(7)-f(6))/(sqrt((f(3)-f(2))^2+(f(7)-f(6))^2+(f(11)-f(10))^2));
(f(11)-f(10))/(sqrt((f(3)-f(2))^2+(f(7)-f(6))^2+(f(11)-f(10))^2));
(f(4)-f(3))/(sqrt((f(4)-f(3))^2+(f(8)-f(7))^2+((f12)-f(11))^2));
(f(8)-f(7))/(sqrt((f(4)-f(3))^2+(f(8)-f(7))^2+(f(12)-f(11))^2));
(f(12)-f(11))/(sqrt((f(4)-f(3))^2+(f(8)-f(7))^2+(f(12)-f(11))^2));
(f(1)-f(4))/(sqrt((f(1)-f(4))^2+(f(5)-f(8))^2+(f(9)-f(12))^2));
(f(5)-f(8))/(sqrt((f(5)-f(8))^2+(f(1)-f(4))^2+(f(9)-f(12))^2));
(f(9)-f(12))/(sqrt((f(1)-f(4))^2+(f(5)-f(8))^2+(f(9)-f(12))^2))];
end
Thanks.

Jan on 13 May 2022
Edited: Jan on 13 May 2022
function dxdt = g(t,f)
dxdt=g(t,f)
...
end
This function calls itself recursively. Of course this let Matlab crash. What is the purpose of "dxdt=g(t,f)"? Simply delete this line to solve this problem.
The code block does not look smart. Compare:
dxdt=[(f(2)-f(1))/(sqrt((f(2)-f(1))^2+(f(6)-f(5))^2+(f(10)-f(9))^2));
(f(6)-f(5))/(sqrt((f(2)-f(1))^2+(f(6)-f(5))^2+(f(10)-f(9))^2));
(f(10)-f(9))/(sqrt((f(2)-f(1))^2+(f(6)-f(5))^2+(f(10)-f(9))^2));
(f(3)-f(2))/(sqrt((f(3)-f(2))^2+(f(7)-f(6))^2+(f(11)-f(10))^2));
(f(7)-f(6))/(sqrt((f(3)-f(2))^2+(f(7)-f(6))^2+(f(11)-f(10))^2));
(f(11)-f(10))/(sqrt((f(3)-f(2))^2+(f(7)-f(6))^2+(f(11)-f(10))^2));
(f(4)-f(3))/(sqrt((f(4)-f(3))^2+(f(8)-f(7))^2+(f(12)-f(11))^2)); % BUG: f12->f(12)
(f(8)-f(7))/(sqrt((f(4)-f(3))^2+(f(8)-f(7))^2+(f(12)-f(11))^2));
(f(12)-f(11))/(sqrt((f(4)-f(3))^2+(f(8)-f(7))^2+(f(12)-f(11))^2));
(f(1)-f(4))/(sqrt((f(1)-f(4))^2+(f(5)-f(8))^2+(f(9)-f(12))^2));
(f(5)-f(8))/(sqrt((f(5)-f(8))^2+(f(1)-f(4))^2+(f(9)-f(12))^2));
(f(9)-f(12))/(sqrt((f(1)-f(4))^2+(f(5)-f(8))^2+(f(9)-f(12))^2))];
With:
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];
This is even faster.

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