Module error 

Chapter 5.0 — Errors

Purpose

Two kinds of failure are reported, never panicked on. The containers (Chapter 5.8) validate outside data — triplets, raw compressed arrays — and report the first violation found as a SparseError, which names the offending array, position and value; every check_invariants() of the crate returns the same type. The factorization reports a singular basis, an inconsistent basis description, or an update called without its spike, as an LuError carrying what the caller needs to recover. Since L1.5 two more kinds join them: the symmetric (KKT) solvers of Chapter 5.14 report a KktError — structure, symmetry, a zero pivot or the wrong inertia (S6) — and the dense kernels of Chapter 5.16 a DenseError.

xingo-core converts both into its CoreError (From impls there): a SparseError maps variant by variant onto the CoreError that the first edition reported, so the messages the solver prints are unchanged.

Invariants

(E1) Singular { rank_deficiency, cols, rows } has rank_deficiency = cols.len() = rows.len() ≥ 1. Replacing, for every k, the basis column at position cols[k] by the logical column of row rows[k] yields a basis whose factorization succeeds (tested in Chapter 5.3); this is the classic basis repair of the simplex method (Koberstein 2005, §8.2.3; HiGHS HFactor::buildSimple rank deficiency handling). (E2) Errors are reported, never repaired silently: a constructor either returns a structure satisfying all of its invariants or an error.

Enums

DenseError

Error raised by a crate::DenseKernel (Chapter 5.16).

KktError

Error raised by a crate::KktSolver (Chapter 5.14).

LuError

Error raised by crate::LuFactor::factorize and crate::LuFactor::update.

SparseError

Structural error of the containers: invariants (C1)–(C4) of Chapter 5.8 or (V1)–(V3) of Chapter 5.8.3 violated by the input, or the basis references of Chapter 5.1 out of range.