My code keeps coming up with "Index Exceeds Array Bounds" help?

n = 0;

t = 0;

deltat = 0.1;

m = 0.44;

Cd = 0.05;

p = 1.29;

Ra = 0.135;

%Find b using the rearranged formula for circumference of a circle.

b = 0.6/(pi()*2);

A = pi()*Ra*b;

% Pre set random values for testing code

x = [12,12,12];

deltat = [0.1];

agravity = [0,0,-9.81];

v = [2,2,2];

vwind = [3,1,2];

vdrag = [2,1,2];

fdrag = [3,2,3];

while x<=100

    n = n + 1;

    t(n+1) = t(n) + deltat;

    x(n+1) = x(n) + v(n).*deltat;

    v(n+1) = v(n) + (agravity(n).*deltat);

end

Answer 1

[Walter Roberson]

You have

agravity = [0,0,-9.81];

so agravity is length 3. You are not storing new agravity entries as you go along like you are for t, x, v, so when you reach n = 4, agravity(n) will be an error.

[Madison Goodwin]

How do I change this? because im meant to be simulating a kick? This is currently what I have, so each value should update as time goes on but I'm not quite sure how to do this? So xx is distance in x , XY is distance in y, XZ is distance in Z. but I want to make this code shorter and nicer, which above I posted my vectorised code

   XX(n+1) = XX(n) + (VX(n))*deltat;
    vdragX(n) = VX(n)- vwindX;
    MagfdragX = norm(fdragX);
    MagfdragX(n) = 0.5*p*A*Cd*(norm(vdragX(n)))^2;
    fdragX(n) = MagfdragX(n)*(-vdragX(n)/(norm(vdragX(n))));
    atotalX(n) = agravityX + fdragX(n)/m;
    VX(n+1) = VX(n) + (agravityX*deltat);
% Y axis
    XY(n+1) = XY(n) + (VY(n))*deltat;
    vdragY(n) = VY(n)- vwindY;
    MagfdragY = norm(fdragY);
    MagfdragY(n) = 0.5*p*A*Cd*(norm(vdragY(n)))^2;
    fdragY(n) = MagfdragY(n)*(-vdragY(n)/(norm(vdragY(n))));
    atotalY(n) = agravityY + fdragY(n)/m;
    VY(n+1) = VY(n) + (agravityY*deltat); 
%Distance & Velocity in z axis direction with drag forces and wind
    XZ(n+1) = XZ(n) + (VZ(n))*deltat;
    vdragZ(n) = VZ(n)- vwindZ;
    MagfdragZ = norm(fdragZ);
    MagfdragZ(n) = 0.5*p*A*Cd*(norm(vdragZ(n)))^2;
    fdragZ(n) = MagfdragZ(n)*(-vdragZ(n)/(norm(vdragZ(n))));
    atotalZ(n) = agravityZ + fdragZ(n)/m;
    VZ(n+1) = VZ(n) + (atotalZ(n)*deltat); 

end

[Madison Goodwin]

So I want to create arrays for each variable such that its got x,y,z quantities. So I have to create a loop that iterates over each value in the array. But I also need to include in that the time is also changing in the loop, and I don't know how? But ive got this so far. Where: t = 0 n = 0 deltat = 0.1,

x = [], v = [], fdrag = [], vwind = [], vdrag = [], agravity= []

    while x<=100

    n = n + 1;

    t(n+1) = t(n) + deltat;

    x(n+1) = x(n) + (v(n).*deltat);

     % Finding Acceleration including other forces

    vdrag = v(n) - vwind(n);

    Magfdrag = norm(fdrag(n));

   Magfdrag(n) = 0.5*p*A*Cd.*(norm(vdrag(n))).^2;

    fdrag(n+1) = Magfdrag(n).*(-vdrag(n)/norm(vdrag(n)));

    atotal(n+1) = agravity(n) + (fdrag(n)./m);

    v(n+1) = v(n) + (atotal(n).*deltat);
end