why my script doesnt run ?

clc;

close all;

syms s t ;

%Space of Time

t = 0:10:15000;

%Kelvie Temperature

t_initial = 423;

%2st case

u_t2 = 50000*heaviside(t)-15000*heaviside(t-2500)+10000*heaviside(t-5000)+8000*heaviside(t-8000);

d_t2 = 288;

%Laplace tranform

U_s2 = laplace(u_t2, s);

D_s2 = laplace(d_t2, s);

%Tranfer Function

Y_s2 = ((0.004)/(1000*s +1))*U_s2 + (1/(500*s + 1))*D_s2 + (1000/(1000*s + 1))*t_initial;

%Inverse Laplace Transform

y_t2 = ilaplace(Y_s2);

y_t2 = subs(y_t2, t);

y_t2 = double(y_t2);

figure(2)

plot(t, y_t2);

xlabel('Time (sec)')

ylabel('y(t)')

title('2nd Case')

grid on;

Answer 1

[Star Strider]

Use fplot not plot here —

syms s t ;
%Space of Time
% % t = 0:10:15000;                             % Commented-Out
%Kelvie Temperature
t_initial = 423;
%2st case
u_t2 = 50000*heaviside(t)-15000*heaviside(t-2500)+10000*heaviside(t-5000)+8000*heaviside(t-8000);
d_t2 = 288;
%Laplace tranform
U_s2 = laplace(u_t2, s);
D_s2 = laplace(d_t2, s);
%Tranfer Function
Y_s2 = ((0.004)/(1000*s +1))*U_s2 + (1/(500*s + 1))*D_s2 + (1000/(1000*s + 1))*t_initial;
%Inverse Laplace Transform
y_t2 = ilaplace(Y_s2);
y_t2 = subs(y_t2, t);
% y_t2 = double(y_t2);                          % Not Possible With Retained Symbolic Variables

figure(2)
fplot(y_t2, [0 1.5E4]);
xlabel('Time (sec)')
ylabel('y(t)')
title('2nd Case')
grid on;

.