function runme() % Putting inside function really important. Compare to without.

N=1e4;
X=rand(N);
y=rand(1,N);
for i=1:4
	tic;Z1=X+diag(y);toc
end
disp('-----')
for i=1:4
	tic;Z2=plus_diag(X,y);toc
end

isequal(Z1,Z2)