This will do those equations:
function L = CalcDistance()
Dx = rand(1,100000);
Dy = rand(1,100000);
Dz = rand(1,100000);
Vx = rand(1,100000);
Vy = rand(1,100000);
Vz = rand(1,100000);
ax = rand(1,100000);
ay = rand(1,100000);
az = rand(1,100000);
t = 2; % it is fixed
x = Dx + Vx*t + 1/2*ax*t^2;
y = Dy + Vy*t + 1/2*ay*t^2;
z = Dz + Vz*t + 1/2*az*t^2;
dx = diff(x);
dy = diff(y);
dz = diff(z);
L = sqrt(dx.^2+ dy.^2+ dz.^2);
Of course you would not use rand(), you'd use the actual arrays, wherever you got them.
