Fc. Silva, POSSIBLE BLOCK SIMILARITY CLASSES OF A MATRIX WITH A PRESCRIBED NONPRINCIPAL SUBMATRIX .2., Linear algebra and its applications, 262, 1997, pp. 259-282
This paper gives necessary and sufficient conditions for the existence
of a matrix [A(1) A(2)], where A(1) is square, with prescribed block
similarity class and a prescribed submatrix that does not contain prin
cipal entries of A(1). (C) Elsevier Science Inc., 1997.