num::randommat::grounded_approx_chol_factor

Defined in header <linear/graph/randommat/preconditioner.hpp>

class grounded_approx_chol_factor final;

Sparse approximate factor C of a grounded SDDM matrix, stored through the Cholesky factor of its one-vertex Laplacian extension.

The ground vertex is pinned last and omitted from all vector actions below.

Members

member	description
using domain_type = vec<real>
using codomain_type = vec<real>
using laws = law::list<law::spd>
explicit grounded_approx_chol_factor(cholesky_factor<real, idx> factor)
idx rows() const noexcept
idx cols() const noexcept
vec<real> apply_lower(const vec<real> &x) const	Apply C, where the approximate grounded matrix is C C^T.
vec<real> solve_lower(const vec<real> &b) const	Apply C^{-1} by forward substitution.
vec<real> solve_upper(const vec<real> &b) const	Apply C^{-T} by backward substitution.
void apply(const vec<real> &b, vec<real> &x) const	Apply the approximate inverse C^{-T} C^{-1} as an SPD preconditioner.
const cholesky_factor<real, idx> &factor() const noexcept