Iranian Mathematical Society (IMS)Bulletin of the Iranian Mathematical Society1017-060X39220130515The least-square bisymmetric solution to a quaternion matrix equation with applications239257340ENQ.WangDepartment of Mathematics, Shanghai UniversityG.YuDepartment of Mathematics, Shanghai UniversityJournal Article20110127In this paper, we derive the necessary and sufficient conditions for the quaternion matrix equation XA=B to have the least-square bisymmetric solution and give the expression of such solution when the solvability conditions are met. Futhermore, we consider the maximal and minimal inertias of the least-square bisymmetric solution to this equation. As applications, we derive sufficient and necessary conditions for XA=B to have the positive (nonnegative) definite least-square bisymmetric solution and the maximal (minimal) least-square bisymmetric solution.http://bims.iranjournals.ir/article_340_5bfe11787a82c95ca80797926f05c97f.pdf