function [x,y]=Euler_d(ydot_fun,x0,y0,h,N)
x=zeros(1,N+1);y=zeros(1,N+1);
x(1)=x0;y(1)=y0;
for n=1:N
    x(n+1)=x(n)+h;
    ybar=y(n)+h*feval(ydot_fun,x(n),y(n));
    y(n+1)=y(n)+h/2*(feval(ydot_fun,x(n),y(n))+feval(ydot_fun,x(n+1),ybar));
    end