x=[0:0.0001:1/10];
l=1000;

clf

e=0.1;
plot(x,exp(-l*x)*e,'r'); % exact solution
hold on

u=[];

u(1)=e;

h=0.00001;
n=round(0.1/h);
for i=1:n
  u(i+1)=1/(1+l*h)*u(i);     
end

 plot([1:n+1]*h,u);