clear
f=@(x) -cos(x);
corr=@(x) cos(x);
L=2*pi;
alpha=1;
beta=1;
k = linspace(1,12,12);
for i= 1:length(k);
    N(i)=2^k(i);
end



for j=1:length(N);
    c=linspace(0,L,N(j)+2);
    c1=0;
    y=0;

    for i= 1:N(j);
       fvec(i)=f(c(i));
       c1(i)=corr(c(i));
    end

c1=[alpha c1 beta];

y=twoBVP(transpose(fvec),alpha,beta,L,N(j));

%plot(c,y);
hold on
err=c1-transpose(y);
plot(L/(1+N(j)),norm(err,inf),'x');
% %grid on
end

%plot(c,corr(c),'-')