Ranks of Solutions of the Matrix Equation AXB = C

The purpose of this article is to solve two problems related to solutions of a consistent complex matrix equation AXB = C : (I) the maximal and minimal ranks of solution to AXB = C , and (II) the maximal and minimal ranks of two real matrices X 0 and X 1 in solution X = X 0 + iX 1 to AXB = C . As applications, the maximal and minimal ranks of two real matrices C and D in generalized inverse (A + iB)- = C + iD of a complex matrix A + iB are also examined.