num::debug::estimate_spectrum_bounds

Defined in header <algebra/debug.hpp>

template <class Op, class VectorType>
auto estimate_spectrum_bounds(const Op &A, idx n, idx iterations = 64);

Estimate {lambda_min, lambda_max} of a self-adjoint operator by power iteration.

The minimum comes from power-iterating \(\lambda_{max} I - A\). Only this separates a definite operator from a semidefinite one, since random probes never land in a null space.