%exercise 7.4
%h med olika startvärden
[t1,h1]=ode23(@waterlevel,[0 20],0);
[t2,h2]=ode23('waterlevel',[0 20],3);
[t3,h3]=ode23('waterlevel',[0 20],10);
plot(t1,h1,t2,h2,'--',t3,h3,'-.'),grid

