It would we good if you could use the sigma value “sr” in function eigs for symmetric matrices, too.
sigma = "sa" work for you?
sigma = "sa"; eigs (A, k, sigma)
eigs function might need some update GNU Octave - Bugs: bug #52999, Syntax change in eigs [Savannah] and the documentation looks confusing to me. Matlab sees both options as equal. Maybe there was a distinction for historical reasons.
Furthermore looking at the implementation and following
sigma through the m-code,
"sr" are identical. Any error messages are “artificial”
There could be some distinction between
"sr" within the
__eigs__.cc internal function, but the easiest check was if replacing the one by the other works for you
“sa” seems to work. Thanks for your help.