Positive semidefinite completions of partial Hermitian matrices

Jerome Dancis
1992 Linear Algebra and its Applications  
We classify the ranks of positive semidefinite completions of Hermitian band matrices and other partially specified Hermitian matrices with chordal graphs and specified main diagonals. Completing a partially specified matrix means filling in the unspecified entries.
doi:10.1016/0024-3795(92)90304-s fatcat:p4r6iihjnff5tgewi2ngpie2eu