how to plot displacement vs time for a vehicle of altering motion PLZ help (

VEHICLE 2

Im trying to plot the displacement of a vehicle for t=0 to t=23 in steps of 0.1

The vehicle has constant velocity of (-20 m/s) for t=0 to t=1 from t=1 to t=6 (total of 5 seconds) it slows down with constant acceleration of (-2),

from t=6 to t=23 its velocity is constant at (-10 m/s)

here is my code, when i try to plot it its stupid and doesnt make sense please

clear all

S=300; %spam of the bridge in m

x0=[0 -5 -15 210 215 225 325 330 395 400]; %initial 'x' positions of vehicles axels (Front,Middle,Rear) (m) v0=[15 15 15 -20 -20 -20 25 25 20 20]; %initial velocity of each axel (m/s) w =[60000 40000 100000 60000 40000 100000 10500 24500 10500 24500]; %load on each axel (N)

s_step = 0.5; t_step = 0.1;

y = [0:s_step:S]; t = [0:t_step:23]; [Y,T] = meshgrid (y,t);

T1 = T(1:231,:); % 0 to 23 seconds T2 = T(1:11,:) ; % 0 to 1 seconds T3 = T(12:61,:); % 1 to 6 seconds T4 = T(13:231,:); %6 to 23 seconds

%Positions of axels of vehicle 1

for i = 1

    X1f(1:231,:) = x0(i) + v0(i)*T1;  %position function of front axel of 
    X1m=X1f-5;
    X1r=X1m-10;

end

%Position of axels of vehicle 2

for i= 4 X2f(1:11,:) = x0(i) + v0(i)*T2; %colum 1 to 11 of X2f.... X2f(12:61,:) = (x0(i)-20)+0.5*(-2)*(T3-1).^2 X2f(13:231,:)= v0(i)*(T4);

    X2m=X2f+5;
    X2r=X2m+10;
end

plot (T,X2f)

I CANT FIND THE ISSUE!