You had many syntax errors on your code. Here is a version with them fixed and it should work. Although a negative weighting is not something that makes sense to me (it happens for t>3.75 s following your command).
clc; clear all
a=0;b=8;h = [0.8 0.5 0.1];yINI = [0;0];
for idxH=1:3
[t,y,ydot] = odeEULER(@dydt,@dydotdt,a,b,h(idxH),yINI);
figure
plot(t,y,'LineWidth',2)
xlabel('Time(s)')
ylabel('Distance travelled(m)')
title(['Displacement over time. h = ',num2str(h(idxH))])
grid on
figure
plot(t,ydot,'LineWidth',2)
xlabel('Time(s)')
ylabel('Velocity (m/s)')
title(['Velocity vs Time. h = ',num2str(h(idxH))])
grid on
end
function dydx=dydt(ydot)
dydx=ydot;
end
function dydx=dydotdt(t,ydot)
g=32.2;
w= 3000-800*t;T = 8000;D =((0.005*g)*(ydot^2));
dydx=((g/w)*(T-w-D));
end
function [t,y,ydot] = odeEULER(ODE1,ODE2,a,b,h,yINI)
%a - initial value for t
%b - last value of t
%h - step size
%yINI - y and y dot initial values
%Output variables- t,y,ydot
N= (b-a)/h;
y = zeros(N,1);
ydot = zeros(N,1);
t = zeros(N,1);
t(1) = 0; y(1) = yINI(1); ydot(1) = yINI(2);
for i=1:N-1
t(i+1)=t(i) + h;
y(i+1)=y(i) + ODE1(ydot(i))*h;
ydot(i+1)=ydot(i) + ODE2(t(i),ydot(i))*h;
end
end
