The second author's research was supported by Program for Innovative Research Team of Shanghai University of Finance and Economics (IRTSHUFE) and by National Natural Science Foundation of China (NSFC) Project 11471205; the third author's research was supported in part by NSF GOALI 0800151.
Recently, researchers have been interested in studying the semidefinite programming (SDP) relaxation model, where the matrix is both positive semidefinite and entry-wise nonnegative, for quadratically constrained qu...