Projectile Motion Hitting a Terrain

Hi all! I am working on a project in which the user inputs an initial velocity and an initial launch angle for a projectile, which will then land and stop when it hits a predefined terrain. I am having trouble getting the projectile to stop once it hits the terrain. Here is a look at my code:

V = input('initial velocity:')
A = input('launch angle:')

x = [];
y = [];

for n = 0:.5:1000
    R = n;
    R2 = .5*n;
    if n <= 300
    x = [x n];
    y = [y R];
    elseif 300 < n && n <= 700
    x = [x n];
    y = [y R2];
    end
end
plot(x,y)
hold on

g = -9.81;

Vx = V*cos(A*pi/180);
Vy = V*sin(A*pi/180);
T = 2*(-Vy)/g;
Px = [];
Py = [];

for t = 0:.5:T
    Z = (Vy*t + .5 * g * power(t,2));
    Px = [Px Vx*t];
    Py = [Py Z];

end

XXX = Px(Px ~= 0);
XXX = round(XXX);
YYY = Py(Py ~= 0);
YYY = round(YYY);

check = 0;

for w = 1:1000
if YYY(w) < y(XXX(w))
    check = 1;
    C = w
     Py = Py(1:C);
     Px = Px(1:C);
    break
end
end
check

plot(Px,Py)

I created the matrices XXX and YYY so that I could check using the for loop at the end of the code. Otherwise, the point (0,0) would bring in problems. I think the problem is that the variable C gives me an x coordinate too large.

Finally, I believe that there is a way to do this using comet and movie animations, but that is beyond my scope of Matlab

Let me know what you think the error is, Thanks!

[Image Analyst]

You forgot to tell us typical values to input that will make a nice looking plot.