Projectile Motion with analytical and numerical analysis.

Can someone help me fix the function? My last plot isn't plotting the curve.

%% HW3 Projectile Motion
clear; clc

%% Experimental
a=-9.8; %gravity
n=1;    %interval
tt=10;  %total time
T=0:n:tt; %time
% equation
x=T;    
yy=a*(T); %F=m*a(t) neglecting mass

%% Analytic Analysis
% falling object without any drag coefficient and air density
%graph Velocity vs. Time

%% inputs
h=1; %step size
tl=0; %lower bound
th=10; %upper bound

vg=100; %initial velocity of golf ball (m/s)
%% establish domain
t=[tl:h:th]; %independent variable (time)
v= zeros(1,length(t)); %dependent variable (velocity)

%% initial condition
y(1)=vg;

%% constants
mg=1; %mass of golf ball
g=-9.8; %gravity

%% define function ODE
f=@(t,y) mg.*g;     %Newton's Second Law equation is f=m.*a

%loop over N 
for i=1:length(t)-1
   % t(i+1)=t(i)+h;                  %Euler's Method
    y(i+1)=y(i)+f(t(i),y(i)).*h;
end


%% Numerical Analysis
%consist of air density, cross sectional area, and Drag Coefficient of
%object

%% inputs
h=0.5; %step size
tl=0; %lower bound
th=10; %upper bound

vg=100; %initial velocity of golf ball (m/s)
%% establish domain
t=[tl:h:th]; %independent variable (time)
v= zeros(1,length(t)); %dependent variable (velocity)

%% initial condition
y(1)=vg;

%% constants
mg=2; %mass of golf ball
g=-9.8; %gravity
rho=1.225; %air density
Cg=0.47; %drag coefficient of a sphere
Ag=0.005; %cross-sectional area of golf ball 

%% define function ODE
f=@(t,y) mg.*g;     %Newton's Second Law equation is f=m.*a

%loop over N 
for i=1:length(t)-1
   % t(i+1)=t(i)+h;                  %Euler's Method
    y(i+1)=y(i)+f(t(i),y(i)).*h;
end

fn=@(t,y) ((1/2.*mg).*(rho).*(Cg).*(Ag).*(vg.^2))+g;

for i=1:length(t)-1
    yn(i+1)=y(i)+fn(t(i),y(i)).*h;
end

%% Plots
figure(1); clf(1)
plot(x,yy,'-.dr');
hold on
plot(t,y,'-o')
hold on
plot(t,yn,'--x')
title('Experimental and Analytic Analysis of a falling golf ball')
xlabel('Time (s)')
ylabel('Velocity (m/s)')
xlim([0 20])
ylim([0 25])

[Image Analyst]

Need more detail. Exactly which variable (yy, y, or yn) is not plotting?

Why is the x axis x for one plot but t for the other two plots?

You don't need clf(1) right after you call figure(1) -- it's already clear/blank!

If you get rid of the calls to xlim and ylim, the plot looks like this: