Plot not displaying lines

I have a simple project here and my plot comes up fine but without any line or points present. Just blank with a scaled X and Y axis. Thoughts?

%Test your might! Who's ball will clear a football field?

disp('Two people see who can throw farther, will they clear the field? Who will win?');

Vi = input('How fast is the first ball released in mph? ');

A = input('At what angle do you release this ball in degrees? ');

Vi1 = input('How fast is the second ball released in mph? ');

A1 = input('At what angle do you release this ball in degrees? ');

%Now we need conversion equations and kinematic equations to find the final

%distances

V_mps = (Vi*0.44704);

A_rad = A*(pi/180);

t_hit = 2*(V_mps/9.8)*sin(A_rad);

dist= ((V_mps*t_hit*cos(A_rad))*1.09361);

t_max = t_hit/2;

x = ((V_mps.*t_max.*cos(A_rad))*1.09361);

y = ((V_mps.*t_max.*sin(A_rad)- 0.5*9.8*t_max^2)*1.09361);

%second throw

V_mps1 = (Vi1*0.44704);

A_rad1 = A1*(pi/180);

t_hit1 = 2*(V_mps1/9.8)*sin(A_rad1);

dist1 = ((V_mps1*t_hit1*cos(A_rad1))*1.09361);

t_max1 = t_hit1/2;

x1 = ((V_mps1.*t_max1.*cos(A_rad1))*1.09361);

y1 = ((V_mps1.*t_max1.*sin(A_rad1)- 0.5*9.8*t_max1^2)*1.09361);

plot (x, y, "r-");

plot (x1, y1, "r--");

%Final if statement to determine if the launch was over or under 100 yards

%and who won

if dist>= 100

fprintf('Player 1, you made it!');

else

fprintf('Player 1, you did not make it :(');

end

if dist1>= 100

fprintf('Player 2, you made it!');

else

fprintf('Player 2, you did not make it :(');

end

if dist> dist1

fprintf('Player 1 wins!');

end

if dist< dist1

fprintf('Player 2 wins!');

end

if dist == dist1

fprintf('It was a tie!')

end

Answer 1

[Adam Danz]

A line requires at least two points. Your x, x1, y, y1 values are scalars (single points). If you want to plot a marker instead of a line,

plot (x, y, "ro");    % circular marker
plot (x1, y1, "rs");  % square marker

Perhaps you meant to plot,

plot ([x, x1], [y, y1], "r-");

[Gerrit Feyen]

okay, this does give me a plot now, just connecting the two max heights. What I'm going for is plotting the height against time intervals on the x axis to get a parabolic graph of the motion. Should I just replace the t_max in my height (y, y1) equations with an increasing time so I get a value at each second?

[Adam Danz]

How does the height vary through time? Which variable represents time and which variable represent height at each time point?

[Gerrit Feyen]

y and y1 were supposed to be the two thrown ball heights, I was copying another set of fuctions for plotting motion with the x and x1 since mine was not working. I want the height of the thrown ball from start to finish plotted as it goes through the air with the y and y1 equations. This is what I just tried and I got errors in my h(t) equations, just what I called y now.

V_mps = (Vi*0.44704);
A_rad = A*(pi/180);
t_hit = 2*(V_mps/9.8)*sin(A_rad);
dist= ((V_mps*t_hit*cos(A_rad))*1.09361);
t_max = t_hit/2;
for t =0:10
    h(t) = ((V_mps.*t.*sin(A_rad)- 0.5*9.8*t^2)*1.09361);
    t = t+1;
end
%second throw

V_mps1 = (Vi1*0.44704);
A_rad1 = A1*(pi/180);
t_hit1 = 2*(V_mps1/9.8)*sin(A_rad1);
dist1 = ((V_mps1*t_hit1*cos(A_rad1))*1.09361);
t_max1 = t_hit1/2;
for t1 =0:10
   h1(t) = ((V_mps1.*t1.*sin(A_rad1)- 0.5*9.8*t1^2)*1.09361);
    t1 = t1+1;
end
y1 = ((V_mps1.*t_max1.*sin(A_rad1)- 0.5*9.8*t_max1^2)*1.09361);

plot ([t,t1],[y,y1], "r-");

Among other issues I think I need to define my variables better for the loops, idk I'm not great at this

[Gerrit Feyen]

*the balls remain in the air for about 5 seconds I believe