function [tout,yout] = euler_tdelillo4(F,tspan,y0,n)
% euler - compare with odetx from Moler's book
t0=tspan(1);
tf=tspan(2);
h=(tf-t0)/n;
t=t0;
y=y0(:);
% Euler loop
for k=1:n
  y(k+1,:) = y(k,:) + h*F(t,y(k,:));
  t(k+1) = t(k) + h;
  tout(
end
  t=t(:); % make t a column vector

