Hermitian Lanczos method descriptor.

Usage

lanczos(
  max_subspace = NULL,
  max_restarts = NULL,
  block = 1L,
  reorthogonalize = TRUE
)

max_subspace: Optional maximum active Krylov subspace size m. Must be at least k + 1. The native thick-restart path keeps the active basis bounded by this value across restart cycles.
max_restarts: Optional non-negative integer giving the maximum number of thick-restart cycles allowed before stopping with whatever has converged. Default 100L.
block: Native block size. 1L selects the scalar thick-restart path; values greater than one select the native block Krylov prototype where supported.
reorthogonalize: Whether to apply full reorthogonalization. The native path always reorthogonalizes (DGKS x2) and ignores this flag; it is preserved for the R reference solver's public API.

An eigencore_method descriptor selecting Lanczos iteration.