superdiagonal
nounEtymology From super- + diagonal.
1
Mathematics, Sciences The diagonal of a matrix that lies directly above and to the right of the main diagonal.
- We classify all free spectrahedra that are circular, that is, closed under multiplication by exp(i t): up to unitary equivalence, the coefficients of a minimal LMI defining a circular free spectrahedron have a common block decomposition in which the only nonzero blocks are on the superdiagonal.2016, Eric Evert, J. William Helton, Igor Klep, Scott McCullough, “Circular Free Spectrahedra”, in arXiv: