Delete points after a certian i>

Hi everyone,

I'm trying to simulate an object orbiting another object. As by now I've made a plot where the position of the object gets updated for every step with a changing acceleration/velocity in order to change the direction of it (I hope it makes sense; the code is below):

   while i<1000

    a_1 = G*M/sqrt(x_p1^2+y_p1^2).*direction_p1; %acceleration
    v0_1 = v0_1+h.*a_1; %velocity being updated with step_size h times acc.

    x_p1 = x_p1+dt*v0_1(1);  y_p1 = y_p1+dt*v0_1(2); % x- og y-position
    plot(x_p1,y_p1,'r.')

   end

Currently it just makes a lot of points which stays there, so that after a couple of orbits, the points are all one big mess placed on top of each other.

Is there a way so that after, let's say, 15 points have been placed the first placed points will start to get deleted so only 15 points will be visible at the time?

(If you can imagine it look like a trail of points after each other with the motion)

I've tried writing something like

 if i>10
    delete(x_p1(i-10))
 end

but then the simulation just stops after i>10. Any ideas on how I can do it?

Answer 1

[Walter Roberson]

If you have R2014b or later, use animatedline()

[NaGi]

I'm not sure how to use animatedline() - isn't there a way with what I've written now or could you maybe tell me what to do to use this with animatedline?

[Walter Roberson]

   an_line = animatedline('MaxinumNumPoints', 15, 'LineStyle', 'none', 'Marker', '.', 'Color', 'r');

   while i<1000

    a_1 = G*M/sqrt(x_p1^2+y_p1^2).*direction_p1; %acceleration
    v0_1 = v0_1+h.*a_1; %velocity being updated with step_size h times acc.

    x_p1 = x_p1+dt*v0_1(1);  y_p1 = y_p1+dt*v0_1(2); % x- og y-position
    an_line.addpoint(x_p1 ,y_p1);
    drawnow();

   end