# Revision history for linear-massiv
## 0.1.0.6 — 2026-11-05
### Multi-Package Migration & Constellation Standards
* Restructured codebase into `packages/linear-massiv/` conforming to the Cellarius project constellation conventions.
* Added standard Gachi repository scaffolding (`AGENTS.md`, `CLAUDE.md`, `PLAN.md`, `STATE.md`, CI workflows, verification scripts).
### Dual-Mode Execution & SIMD Cleanliness
* Strict SIMD isolation: all GHC `DoubleX4#` SIMD primops and vector operations are strictly confined to `Numeric.LinearAlgebra.Massiv.Internal.Kernel` behind `#ifdef USE_SIMD`.
* Portable unboxed pure scalar fallback: implemented full scalar kernel fallbacks across all BLAS, solver, and decomposition operations, enabling zero-configuration builds on all CPU architectures (x86_64, ARM64 / Apple Silicon, RISC-V).
* Zero NCG panics: eliminated Native Code Generator vector extract panics on GHC 9.14 by defaulting `simd` flag to `False`.
* Multi-GHC portability: verified compatibility across GHC 9.6.7, 9.8.4, 9.10.3, 9.12.4, and 9.14.1 (`base >= 4.18 && < 5`).
* Optional SIMD acceleration: AVX2 SIMD vectorisation enabled via `cabal build --flags=simd --ghc-options="-fllvm -pgmlo opt-17 -pgmlc llc-17 -mavx2 -mfma"`.
### Test Suite Additions
* Added `Test.Linear` covering `Linear.V` roundtrip conversions, `fromV2`, `fromV3`, `fromV4` indexing, and `toListMatrix`/`fromListMatrix` dimension checking.
* Added `Test.Banded` covering `bandLU`, `bandForwardSub`, `bandBackSub`, `bandCholesky` (for bandwidths $p=1$ and $p=2$), and `tridiagSolve`.
* Extended `Test.Eigen` with test cases for `inverseIteration` and `rayleighQuotient`.
### Documentation & Performance Framing
* Fully overhauled `README.md` and package documentation with honest Golub & Van Loan algorithmic framing.
* Retracted universal "faster than BLAS/LAPACK" benchmark claims in favour of transparent runtime overhead discussion and unboxed kernel engineering.
* Fixed Haddock identifier resolution warnings across `Numeric.LinearAlgebra.Massiv.Linear` and `Numeric.LinearAlgebra.Massiv.Eigen.SVD`.
### Licensing Modernisation
* Re-licensed to EUPL-1.2 OR Apache-2.0 dual license for compliance with German and broader EU software procurement standards, matching the Cellarius constellation policy.