u=zeros(1,100);   % u is the wave displacement
vu=zeros(1,100);	% vu is the velocity of the string

% here would be the initial conditions and initial velocities,,,,

dx=1;   % each x step is 1 meter
v=10;   % wave velocity is 10 m/s

dt=0.05;  % timestep is 0.01 seconds

h=plot(u)
axis([1,100,-1,1])



t=0;
while 1			% do it until someone hits cntrl-c

  t=t+dt
  au=zeros(1,100);		% au will be the acceleration vector
  oldu=u;		% save the previous value of u

% here's where we would add any forcing, by forcing u(1) to be
% a particular value

  
  for i=2:99 		% step through all of the spatial steps
    au(i)=v^2/dx^2*(u(i-1)-2*u(i)+u(i+1));	% second spatial derivative
  end
  vu=vu+dt*au;		% v=v0+a*t
  u=u+vu*dt+au*dt*dt/2;	% s=1/2at^2+vt

   set(h,'YData',u,'Color',[0,0,1])  % overplot a blue line
   set(h,'Color',[1,0,0])               % overplot a red line
   drawnow       
end

end