  Pointwise and ergodic iteration-complexity results for the proximal
alternating direction method of multipliers (ADMM) for any stepsize
in(0,(1+\sqrt{5})/2) have been recently established in the literature. In
addition to giving alternative proofs of these results, this paper also extends
the ergodic iteration-complexity result to include the case in which the
stepsize is equal to (1+\sqrt{5})/$. As far as we know, this is the first
ergodic iteration-complexity for the stepsize (1+\sqrt{5})/2 obtained in the
ADMM literature. These results are obtained by showing that the proximal ADMM
is an instance of a non-Euclidean hybrid proximal extragradient framework whose
pointwise and ergodic convergence rate are also studied.
