Struct ArpackOptions 

pub struct ArpackOptions {
    pub nev: usize,
    pub which: ArpackWhich,
    pub tol: f64,
    pub ncv: usize,
    pub mxiter: usize,
    pub mode: ArpackMode,
    pub start: Option<Vec<f64>>,
}

Options of the ARPACK eigensolvers (a safe subset of igraph_arpack_options_t).

Default gives igraph’s defaults (igraph_arpack_options_init): one eigenvalue of largest magnitude, machine precision tolerance, automatic number of Lanczos/Arnoldi vectors, at most 3000 iterations, regular mode and a random start vector (drawn from igraph’s RNG, so results are reproducible after rng::seed).

The functions that pick which and nev themselves (e.g. eigen_matrix_symmetric, Graph::eigen_adjacency or the spectral embeddings) ignore those fields as well as ncv, mode and the start vector: they only use tol and mxiter.

use igraph::linalg::{ArpackOptions, ArpackWhich};
let opts = ArpackOptions::default().with_nev(3).with_which(ArpackWhich::SmallestAlgebraic).with_tol(1e-10);
assert_eq!(opts.nev, 3);
assert_eq!(opts.mxiter, 3000);

Fields

nev: usize

Number of eigenvalues to compute (nev), at least 1 and smaller than the order of the matrix (at most n - 2 for non-symmetric problems).

which: ArpackWhich

Which eigenvalues to compute.

tol: f64

Relative accuracy of the Ritz values; 0 means machine precision.

ncv: usize

Number of Lanczos (Arnoldi) vectors; 0 lets igraph choose. Otherwise it must satisfy nev < ncv <= n.

mxiter: usize

Maximum number of Arnoldi update iterations.

mode: ArpackMode

Regular or shift-and-invert mode.

start: Option<Vec<f64>>

Starting vector (length n); None draws a random one.

Implementations

impl ArpackOptions

pub fn with_nev(self, nev: usize) -> Self

Sets the number of eigenvalues to compute.

pub fn with_which(self, which: ArpackWhich) -> Self

Sets which eigenvalues to compute.

pub fn with_tol(self, tol: f64) -> Self

Sets the tolerance.

pub fn with_ncv(self, ncv: usize) -> Self

Sets the number of Lanczos/Arnoldi vectors (0 = automatic).

pub fn with_mxiter(self, mxiter: usize) -> Self

Sets the maximum number of iterations.

pub fn with_shift_invert(self, sigma: f64) -> Self

Selects the shift-and-invert mode with the given shift.

pub fn with_start(self, start: Vec<f64>) -> Self

Sets the starting vector.

Trait Implementations

impl Clone for ArpackOptions

fn clone(&self) -> ArpackOptions

Returns a duplicate of the value.

fn clone_from(&mut self, source: &Self)

Performs copy-assignment from source.

impl Debug for ArpackOptions

fn fmt(&self, f: &mut Formatter<'_>) -> Result

Formats the value using the given formatter.

impl Default for ArpackOptions

fn default() -> Self

Returns the “default value” for a type.

impl PartialEq for ArpackOptions

fn eq(&self, other: &ArpackOptions) -> bool

Tests for self and other values to be equal, and is used by ==.

fn ne(&self, other: &Rhs) -> bool

Tests for !=. The default implementation is almost always sufficient, and should not be overridden without very good reason.

impl StructuralPartialEq for ArpackOptions