WHAT: ext/SparseWithDenseRowColMatricesLinearSolveExt.jl has zero references to lstsq/LeastSquares/pinv. Both existing algs (SWDRCFactorizationAlg, SWDRCQRFactorizationAlg) map a singular A to ReturnCode.Infeasible (lines 104-106, 166-168), so there is no way to get the min-norm A⁺b through the LinearSolve interface despite the full lstsq machinery existing. WHY IT MATTERS: LinearSolve is the standard SciML entry point and the natural home for the cached factorization; users in a LinearSolve pipeline cannot reach lstsq at all. FIX: Add SWDRCLeastSquaresAlg (mirroring the QR alg): init_cacheval builds a SparseWithDenseRowColLeastSquares (dense-COD fallback when structured doesn't apply), solve! does ldiv!(cache.u, F, cache.b), and once the LS refactor! lands its _refresh! reuses symbolic analysis across cache.A updates. Expose a public SparseWithDenseRowColLeastSquaresFactorization(; alg=:auto, tolC=...) in src/factorize.jl. Add a test/test_linearsolve.jl block (currently only LU+QR algs tested). Best done after or alongside the LS refactor! issue. EFFORT: M.
Priority: high. Filed from an automated next-steps audit of the QR/lstsq work (see PR #6).
WHAT: ext/SparseWithDenseRowColMatricesLinearSolveExt.jl has zero references to lstsq/LeastSquares/pinv. Both existing algs (
SWDRCFactorizationAlg,SWDRCQRFactorizationAlg) map a singular A toReturnCode.Infeasible(lines 104-106, 166-168), so there is no way to get the min-norm A⁺b through the LinearSolve interface despite the full lstsq machinery existing. WHY IT MATTERS: LinearSolve is the standard SciML entry point and the natural home for the cached factorization; users in a LinearSolve pipeline cannot reach lstsq at all. FIX: AddSWDRCLeastSquaresAlg(mirroring the QR alg):init_cachevalbuilds aSparseWithDenseRowColLeastSquares(dense-COD fallback when structured doesn't apply),solve!doesldiv!(cache.u, F, cache.b), and once the LSrefactor!lands its_refresh!reuses symbolic analysis across cache.A updates. Expose a publicSparseWithDenseRowColLeastSquaresFactorization(; alg=:auto, tolC=...)in src/factorize.jl. Add a test/test_linearsolve.jl block (currently only LU+QR algs tested). Best done after or alongside the LSrefactor!issue. EFFORT: M.Priority: high. Filed from an automated next-steps audit of the QR/lstsq work (see PR #6).