“…Problems of finding the best approximation to a given matrix subject to different kinds of linear constraints, symmetry and positive semidefiniteness are discussed in [4,5,6,7,8,9,10,11,12,13,14,15]. Problems containing zero/nonzero pattern constraint and linear constraints can be found in [16,17,18,19,5,20,21]. Recently, Yuan [22] considered problem (1) using subgradient algorithm for two different models.…”