How to plot forcing function in matlab

function [xdot]=External_input(t,x)

x1=x(1);
x2=x(2);

m=2;
g=9.8;
k=0.15;
J=0.125;
x1dot=x2;
x2dot=((m*g*k*sin(x1))-ui(t))/J;
xdot=[x1dot;x2dot];
end
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%

clc
clear all;close all

t=linspace(0,10,1000);
x0=[0 0];
[t,x,u]=ode45(@External_input,t,x0);
% x1=x(1);
% x2=x(2);
subplot(211);plot(t,x(:,1),'linewidth',2);grid on ;title('Pos')
subplot(212);plot(t,x(:,2),'linewidth',2);grid on ;title('Vel')
figure(2)
plot(t,u)
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%f
function u=ui(t)
% For impulse
eps=0.1;   
if t<eps
      u=1;
  else
     u=0;
end

end %%%%%%%%%%%%%%%%%%%%%%%%%%%%5 Question is %%%%%%%%%%%%%%%%%%%%%

i also want to plot u input ,,,but i am unable to plot it ...can some one guide me how can i plot the u input forcing function (which i have written in a separate function )

thanks