function runme2() % Putting inside function really important. Compare to without.

N=5e3;

for i=1:4
	X=rand(N);
	y=rand(N,1);
	
	tic;X=X+diag(y);toc
	
	clear X y;
	
	X=rand(N);
	y=rand(N,1);
	
	tic;X=plus_diag(X,y);toc
	
	clear X y;
	
	X=rand(N);
	y=rand(N,1);
	
	tic;
	diagidx=(0:N-1)*N+(1:N);
	X(diagidx)=X(diagidx)+y(:)';
	toc

	clear X y;
	
	X=rand(N);
	y=rand(N,1);
	
	tic;
	ip_plus_diag('X','y');
	toc

	clear X y;

	disp('-----');
end

X=rand(N);
X0=X;
y=rand(N,1);

ip_plus_diag('X','y');
isequal(X,X0+diag(y))