function svd1
N=10;
A=sparse(N,N);
onecol=ones(N,1);
A(:,1)=onecol;
A(1,:)=onecol';
[U, S, V] = svds(A);
diag(S)
Arank2=S(1,1)*U(:,1)*V(:,1)'+S(2,2)*U(:,2)*V(:,2)';
norm(A-Arank2)
end
