Does anyone had this plotting problem with MATLAB?

[Cassius1n]

I have finsihed my work on an orbit propagator in MATLAB and now I'm trying to simulate the orbit with the help of the main script.

tspan=[0 :860];

Position and velocity
y0(1,1)= 743322.3616 ;
y0(2,1)= -6346021.219 ;
y0(3,1)= -3394131.349 ;
y0(4,1)= 5142.38067;
y0(5,1)= 4487.44895 ;
y0(6,1)= -7264.00872;

%%%% Mass(kg) /surface(m^2)

m = 217 ; %320;
A = 1.2; %8;

%%%% RK4

h=1;
y = zeros(6, tspan(end)/h);
y(:,1) = y0;

for i=1:1:(tspan(end)/h)

H=sqrt(y(1,i)^2+y(2,i)^2+y(3,i)^2);
k_1 = proiectia(tspan(i), y(:,i), H, m, A, y(4:6, i));
k1=k_1;
k_2 = proiectia(tspan(i)+0.5*h, y(:,i)+0.5*h*k_1, H, m, A, y(4:6, i));
k2=k_2;
k_3 = proiectia((tspan(i)+0.5*h), (y(:,i)+0.5*h*k_2), H, m, A, y(4:6, i));
k3=k_3;
k_4 = proiectia((tspan(i)+h),(y(:,i)+k_3*h), H, m, A, y(4:6, i));
k4=k_4;

y(:,i+1) = (y(:,i) + (1/6)*(k1+2*k2+2*k3+k4)*h);
plot3(y(1,:),y(2,:),y(3,: ));
drawnow

end

The orbit is well described but it keeps drawing an extra line from 0 to where the point(x,y,z) is .After all the values are being represented, the line from 0 dissapears and it only remains the curved line(the orbit). Does anyone have any ideea why does it plot that line from 0 while is on the Runge Kutta loop?

 

[FactChecker]

It bothers me that your assignment of y(:,i+1) = (y(:,i) + (1/6)*(k1+2*k2+2*k3+k4)*h); assigns one beyond the second dimension, tspan(end)/h, of y. Maybe that is causing a problem at the end of the plot of y. It would help us if you can tell us which end of y that zero point is. Is it at y(:,1) or at y(: tspan(end)/h)?

 

[Cassius1n]

That would be at at y(: tspan(end)/h).

 

[FactChecker]

Just as a quick test, you should increase the initialization dimension of y to y = zeros(6, tspan(end)/h + 1); and see if that solves anything. You are making an assignment beyond the current dimension.

 

[Cassius1n]

It's still plotting with the line from 0.