boundlab.ops.definiteness_split

boundlab.ops.definiteness_split(matrix)

Split matrix as pos + neg by shifting the shared diagonal.

Both halves keep the off-diagonal \(M/2\); their diagonals are shifted by \(\pm(\sum_j M_{ij} + \sum_i M_{ij})/4\), pushing pos toward diagonal dominance (hence positive semidefiniteness) and neg the opposite way, so each half’s quadratic form can be bounded one-sidedly.