Struct ShiftedDiagonalPreconditioner 

pub struct ShiftedDiagonalPreconditioner { /* private fields */ }

Diagonal preconditioner for the SHIFTED systems (A + tI) a rational log-determinant plan solves.

The caller supplies the unshifted operator’s diagonal; the shift is added per solve, exactly as it is added to the operator. That single fact is what makes one diagonal serve the whole shift ladder: diag(A + tI) = diag(A) + t.

diagonal: None is the identity, i.e. the unpreconditioned iteration. On the overcomplete arrow border the supplied diagonal is the shared block’s own — the atom FIRING-COUNT distribution, orders of magnitude wide — and it is exactly the spread that stalls an unpreconditioned CG (#2576).

Implementations

impl ShiftedDiagonalPreconditioner

pub fn from_operator_diagonal(diagonal: &Array1<f64>) -> Self

Build from the unshifted operator’s diagonal. A non-finite or non-positive entry means there is no usable scale, and the identity is returned rather than a fabricated one: the iteration is then exactly the unpreconditioned one, which is still correct for SPD A.

pub fn identity() -> Self

pub fn is_identity(&self) -> bool

Whether this preconditioner does anything.

Trait Implementations

impl Clone for ShiftedDiagonalPreconditioner

fn clone(&self) -> ShiftedDiagonalPreconditioner

Returns a duplicate of the value.

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

Performs copy-assignment from source.

impl Debug for ShiftedDiagonalPreconditioner

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

Formats the value using the given formatter.