# Changelog All notable changes to this project will be documented in this file. The format is based on [Keep a Changelog](https://keepachangelog.com/en/1.0.0/), and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0.html). ## [Unreleased] ## [1.9.4] - 2026-08-10 ### Documentation - Published a machine-readable numerical-evidence catalogue for every stable capability family, with bounded domains, edge cases, evidence categories, budgets, test links, and reproducible reference provenance. - Added a human-readable evidence report that distinguishes exact properties, reference comparisons, residual/reconstruction checks, and feasibility diagnostics without claiming universal numerical proofs. ### Validation - Added offline catalogue validation to reject missing or malformed coverage, invalid numerical budgets, absent cited sources/tests, and inconsistent high-risk fault-injection records. - Added isolated compile-and-test mutation checks for scalar special functions, typed dense direct solving, and Bluestein DSP transforms; each sampled fault must be detected by FPCUnit. ## [1.9.3] - 2026-08-04 ### Documentation - Completed the proposed 2.0 API decision by classifying every exact 1.9 declaration, publishing a 13-domain common-path map, and resolving shared naming, shape, ownership, error, tolerance, outcome, RNG, callback, and thread-safety conventions. - Gave every compatibility declaration a named typed replacement with semantic differences or an explicit retain decision, and published an exact empty source/behavior/warning/packaging diff separate from documentary defaults. - Reviewed all 21 plain compiler aliases for identical behavior, defaults, ownership, exception identity, and numerical results. Retained 17 aliases and routed the four pressure/velocity facade and error aliases to 1.9.7 migration and package-boundary confirmation without deprecating them. - Routed ergonomic 2-D and 3-D vector rotation to focused 1.10.0 design work without adding an unreviewed patch-release declaration. ### Validation - Added exact decision, selector/overload, generic-owner, domain/unit, alias-review, compatibility, common-example, convention, and proposed-diff checks to the release qualification suite. - Regenerated the exhaustive 2,880-row API reference with five-way classifications and compatibility decision/note columns while preserving all frozen 1.9 interface hashes. ## [1.9.2] - 2026-08-02 ### Documentation - Added a double-real beginner guide, task-oriented recipe index, and explicit beginner-to-advanced routes for every stable domain without changing the frozen 1.9 public API. - Added searchable routes for dense and sparse solves, descriptive and streaming statistics, probability, interpolation and fitting, optimisation, FFT and filtering, time series, finance, geometry, and unit conversion. ### Validation - Made each beginner recipe's code and claimed output part of the clean- archive documentation checks, including all 13 domain routes, generated problem-oriented search results, local links, release identity, and exact public declarations. - Made checked-heap qualification capture heaptrc in an explicit cross-platform log, reject missing or nonzero summaries numerically, and preserve evidence artifacts even when a qualification job fails. ## [1.9.1] - 2026-08-02 ### Fixed - Replaced seeded bootstrap's private low-bit LCG/modulo sampling with the shared explicit-state generator's unbiased bounded-index path. Eight-element samples no longer collapse every resample to the same mean; a permanent regression covers varying resamples, non-degenerate confidence bounds, deterministic replay, and unchanged global random state. ### Documentation - Added release-identified versioned static documentation, preservation of the tagged 1.9.0 site, and a deterministic offline HTML ZIP plus SHA-256 file. - Made every output-producing runnable documentation program verify its claimed output, and added checked statuses/final markers for the release- facing dense, sparse, and migration examples. - Added a focused feedback route for installation time, type choice, conversions, unexpected errors/statuses, selection guidance, and migration. ### Validation - Added clean-archive qualification automation for normal, optimised, checked/heap-traced, examples, documentation, Lazarus package, quick-start, and benchmark gates, while preserving the exact 1.9 public API snapshot. - Recorded the release evidence and unchanged limitations in `docs/QUALIFICATION_1.9.1.md`. ## [1.9.0] - 2026-08-01 ### Added - Immutable validated CSR/CSC and diagonal/tridiagonal/band storage for single/double real and complex values, deterministic triplet construction, sparse arithmetic/products, and explicit dense conversions. - Typed retained/delegated linear operators and identity, diagonal, IC(0), and ILU(0) preconditioners with documented ownership and reentrancy. - CG, MINRES, restarted GMRES, BiCGSTAB, and LSQR with shared options, true-residual diagnostics, cancellation/progress, breakdown reasons, and reusable scalar-specific workspaces. - Reusable pivoted tridiagonal/no-pivot band factors and an explicit natural-order sparse LU baseline with multiple RHS and fill diagnostics. - Deterministic restarted largest-magnitude Lanczos and Arnoldi with independently checked residuals. - Matrix Market coordinate double-real/double-complex sparse exchange and versioned checksummed four-scalar sparse binary interchange. - End-to-end sparse and candidate-2.0 migration examples, a classified machine-readable public-API snapshot, declaration/default documentation checks, capability records, and large no-densification benchmarks. ### Validation - Added dense-oracle, canonical/malformed interchange, status/breakdown, factor/preconditioner/workspace reuse, in-place alias, concurrent immutable reuse, and 20,000-dimensional no-densification fixtures. - Corrected matrix-free shape validation to bound vector axes independently, preserving large linear-storage workloads on Win32 without weakening invalid-dimension or address-space checks. - Recorded 100,000-nonzero sparse and 200,000-dimensional matrix-free `-O3` qualification cases with nonzero/allocation/storage/product/iteration/ residual/timing evidence. - The complete platform, package, example, documentation, and archive matrix is recorded in `docs/QUALIFICATION_1.9.0.md`. ### Compatibility - Existing public signatures, defaults, and `TMatrixKitSparse` behavior remain available. Legacy-to-typed sparse conversion is explicit. - The 2.0 contract and migration example are preview evidence only. No 2.0 removal, default change, or later-roadmap implementation is included. ## [1.8.0] - 2026-07-30 ### Added - Explicit local xoshiro256** random state and constant-memory mergeable online statistics, with replay, split-stream, and bounded-state tests. - Arbitrary-length/single/batched/2-D FFTs, direct/FFT/overlap convolution, correlation, rational resampling, spectra, analytic signals, Haar transform, and bounded block/FIR/biquad processing. - Paired distribution APIs, parameter estimates, common inference/effect/ correction results, SVD OLS diagnostics, and separation-aware binary logistic regression. - Typed-dense PCA, seeded k-means++, hierarchy, fitted standardization, deterministic splits, binary LDA, seeded classification/regression forests, an exact low-dimensional KD tree, and scalar/multivariate Kalman filtering. - Invariant text, delimited text, a dense Matrix Market subset, and versioned checksummed little-endian numerical and random-state persistence. - Versioned selected-model adapters, typed metadata/complex summaries, and a resource-bounded scalar/vector/matrix expression evaluator. - Audited 1.7 gap closure: classical spline boundaries, explicit complex-step and vector AD, cubature/local-RNG Monte Carlo, scaled/covariance-aware fitting, complex polynomial roots, component ODE tolerances, detailed optimization/workspaces, two-phase simplex, and QP outcome certificates. - Deterministic serial blocked and automatic typed dense multiplication using the portable kernels as cross-path correctness oracles. - Cross-domain and interchange/replay examples, capability records, release notes, benchmark comparison, and qualification evidence. ### Fixed - Made simultaneous complex polynomial-root initialization non-conjugate-symmetric, removing a platform-rounding-dependent Win32 convergence failure. ### Validation - Release-qualified on 2026-07-30 with 899 passing tests under Win64 normal, `-O3`, and checked-heap builds, plus 899 passing tests under Win32 `-O2`. - Built and ran all 22 examples, built both Lazarus packages for Win64 and Win32, and passed documentation checks covering 50 pages, 22 examples, and 248 public symbols. - Rebuilt and verified the checksummed clean source archive, then reran its 899-test suite, all 22 examples, and documentation checks. - Passed the required Linux and Windows GitHub Actions pull-request and push workflows on the qualified release branch. ### Compatibility - Existing 1.7 and earlier public signatures remain available. The 1.8 APIs are additive; the legacy `EngineeringLib.Signal` FFT remains unchanged. - No parallel/SIMD ABI, advanced filter-design/broader-wavelet surface, survival/factor/robust-covariance family, implicit stiff ODE, or general model/decomposition persistence is claimed stable. ## [1.7.0] - 2026-07-30 ### Added - Reusable barycentric, rational, PCHIP, Akima, bilinear/bicubic, IDW, RBF, and thin-plate interpolation with explicit ownership and scale limitations. - Scale-aware finite gradients/Jacobians/Hessians, forward dual-number automatic differentiation, and pre-solve derivative checking. - Adaptive Gauss-Kronrod finite/improper integration, deterministic quasi-Monte-Carlo integration, typed-QR linear fitting, damped robust nonlinear least squares, vector Newton equations, and adaptive Dormand-Prince ODEs with dense output and event detection. - A shared `TIterationStatus` diagnostic vocabulary and dense convex QP/SOCP workflows with objective, feasibility, optimality, iteration, and evaluation results. - End-to-end modelling and convex-optimisation examples, selection guides, tests, capability records, release notes, and qualification evidence. ### Changed - `PenaltyMethod` and `Maximize` no longer serialize through unit-global callback bridges; their callback paths are reentrant. - The Lazarus package and distribution metadata now identify version 1.7.0 and include every new unit. ### Compatibility - Existing 1.6 and earlier public signatures remain available. The 1.7 APIs are additive. ## [1.6.0] - 2026-07-27 ### Added - Added reusable single/double real/complex Householder QR and column-pivoted QR factors, full-rank and rank-revealing least-squares solves, copied compact factors/permutations, numerical-rank decisions, and inspectable residual/backward-error diagnostics. - Added reusable compact one-sided Jacobi SVD factors for tall, square, and wide matrices plus vector/multiple-RHS rank-deficient and underdetermined minimum-norm solves. - Added full ascending symmetric real and Hermitian complex eigensystems with normalized eigenvectors, deterministic cyclic-Jacobi convergence outcomes, and single/double scalar parity. - Added lower/upper, unit/non-unit triangular solves for ordinary, transposed, and conjugate-transposed systems. - Extended LU and Cholesky factors additively with `ConditionIndicator` and `SolveWithInfo`, and added diagnostic square and positive-definite convenience entry points without changing the 1.5 solve contract. - Added the 1.6 design record, solver-selection and migration guides, realistic calibration/minimum-norm/eigen example, capability metadata, focused public/numerical tests, deterministic factor-reuse benchmarks, release notes, and qualification report. ### Compatibility - Preserved every `IMatrix`, `TMatrixKit`, `IVector`, and typed 1.5 entry point. No API was removed or deprecated, and compatibility decompositions are not silently rerouted where their contracts differ. ## [1.5.0] - 2026-07-26 ### Added - Added 32-byte-aligned contiguous row-major single/double real/complex dense matrices with checked native-size shapes, retained-owner mutable views, explicit clones, and explicit compatibility conversions. - Added matching allocating and `Into` dense kernels for elementwise arithmetic, AXPY, scalar-function application, reductions, transpose/conjugation, compensated products, and dot products. - Added allocation-free operator-friendly 2x2 real/complex value matrices, batch types, and explicit flat/nested, precision, real/complex, and compatibility conversions. - Added pivoted-LU `Solve(A, B)`, reusable LU factors, and real/complex Cholesky factors for vector and multiple right-hand sides. - Added `TSingleComplex`, the typed dense migration/design guides, capability inventory, support matrix, solve example, benchmark, and completion-gate tests. ### Compatibility - Preserved `IMatrix`, `TMatrixKit`, `IVector`, and all existing unit entry points. No API was removed or deprecated. ## [1.4.0] - 2026-07-25 ### Added - Added componentwise `+`, binary and unary `-`, scalar `*` in both operand orders, and vector/scalar `/` operators for `GeometryLib.Geometry` `TVector2D` and `TVector3D`. The fixed-size value records retain IEEE-754 `Double` results for signed zero, NaN, infinity, overflow, and zero-scalar division without mutating either operand. - Added focused GeometryLib operator, edge-case, algebraic-property, and public-API smoke coverage, plus a runnable Theodorus-spiral demonstration in the geometry example. ### Fixed - Made `TVector2D` and `TVector3D` magnitude and normalization scale-safe for finite tiny and large components. Normalization now accepts every finite non-zero vector and rejects exact-zero or non-finite vectors explicitly. ## [1.3.0] - 2026-07-23 ### Added - Added the 1.3.0 complex and vector foundation with `MathBase.Complex`: the double-precision `TComplex` record, stable arithmetic and magnitude, principal elementary functions, and `TComplexArray`. - Added `AlgebraLib.VectorKernels` and its `TVectorKit` facade for finite, contiguous real and complex array-vector arithmetic, including scale-safe norms and conjugating complex dot products. `AlgebraLib.Vectors` continues to preserve the existing matrix-as-vector aliases while re-exporting the new array-vector API. - Added `TComplexArray` FFT/IFFT overloads that preserve the existing split-real/imaginary signal API, documentation, a runnable complex-vector example, and focused tests. - Hardened complex division and principal branch behavior, added inverse complex trigonometric and hyperbolic functions, and made `TComplexArray` the native FFT representation. - Expanded vector kernels with stable reductions, elementwise arithmetic, and allocation-avoiding `...Into` destination-buffer procedures. - Added representative complex, vector, and FFT benchmarks plus public API smoke coverage. ### Fixed - Preserved tiny `CAsinh`/`CAtanh` inputs and replaced target-sensitive `z*z` cancellation with scaled component formulas for large inverse complex functions. - Defined infinity/NaN behavior for complex magnitude, exponential, and square root calculations, and retained signed-zero branch sides for inverse hyperbolic functions. - Updated CI to compile and execute the standalone `.pas` examples after their rename from `.lpr`. ## [1.2.3] - 2026-07-21 ### Changed - Reworked `MathBase.Precision` around a higher-accuracy Lanczos log-gamma, cancellation-resistant beta evaluation, convergence-checked incomplete-beta fractions, and direct incomplete-gamma normal tails. - Normal, lognormal, beta, Student-t, and F survival functions now evaluate upper tails directly instead of subtracting a rounded CDF; F-distribution arguments avoid overflowing `d1*x`. Normal-tail approximations in statistics use the same direct-tail path. - Hyperbolic and inverse-hyperbolic helpers preserve tiny arguments and avoid unstable exponential/logarithmic cancellation. Two-dimensional vector magnitude now uses the scaled hypotenuse kernel. ### Fixed - Corrected `MathBase.Precision.StudentT` to use the required `df/2` incomplete-beta shape parameter instead of `(df+1)/2`, fixing t-test p-values built on the shared helper. - Invalid low-level special-function shape parameters now return NaN predictably, and iterative special functions no longer return an unconverged partial result. - Rebased the K-S normality reference on the full-precision normal CDF instead of the previous low-accuracy error-function approximation, and made its empirical CDF fractions explicitly double precision across FPC targets. ### Tests - Added special-function reference, symmetry, invalid-input, small-argument, large-vector, and representable extreme-tail regressions, bringing the suite to 798 tests. Cross-platform cases now pin complement inputs and empirical fractions to `Double` before comparing extreme-tail and K-S references. ## [1.2.2] - 2026-07-18 ### Documentation - Added newcomer-oriented MathBase and NumericsLib walkthroughs, giving every documented domain a runnable example, plus an indexed learning path for all 14 examples. - Reviewed all examples for concise purpose, input, interpretation, and method- selection guidance; corrected the statistics walkthrough to use a local, reproducible bootstrap seed and clarify p-value interpretation. - Added 1.2.2 release notes and updated version and release references. ### Tooling - Added shell and PowerShell entry points that compile every example into an ignored `example-bin/` directory, and made CI exercise both the scripts and the resulting programs on their native platforms. ## [1.2.1] - 2026-07-18 ### Documentation - Defined consistent terminology for the mathlib-fp project, domains, Pascal unit families, units, Kit classes, focused aliases, and the Lazarus package. - Added a public API naming inventory and aligned guides, source headers, and contributor guidance with it without renaming existing public identifiers. ### Tests - Added compile-time smoke coverage for every documented Kit class and focused alias, and registered the existing Engineering focused-alias tests in the main test runner, bringing the current suite to 789 tests. ## [1.2.0] - 2026-07-18 ### Added - `EngineeringLib.Common` with `EEngineeringError` and domain-specific exceptions for fluid dynamics, thermodynamics, signals, and unit conversion. - Seeded `CreateRandom`, `BootstrapMean`, and `BootstrapConfidenceInterval` overloads that are reproducible without changing global random state. - `PolynomialFeatures(..., IncludeBias)` overload so callers can omit the bias column when fitting models that already estimate an intercept. - Edge, property, residual, deterministic-randomness, FinanceLib focused-unit, rounding, UTF-8, parallel-multiplication, and numerical reference coverage, bringing the suite to 788 tests. - Representative performance benchmarks for statistics sorting, convex hulls, and dense matrix multiplication, with CI compilation coverage. - Focused `EngineeringLib.Velocity` and `EngineeringLib.Pressure` entry units now expose directly nameable exception aliases and have direct compilation and runtime coverage. ### Changed - Replaced hard-coded eigendecomposition and power-method cases with general real algorithms and residual-based convergence checks. - Fractional matrix powers now use the symmetric eigendecomposition and require a symmetric positive-definite matrix; integer powers use exponentiation by squaring. - Matrix multiplication uses an operation-count threshold, caps worker count, propagates worker failures, and falls back safely on Unix programs without a thread manager. - ML entry points consistently reject empty, ragged, non-finite, mismatched, or out-of-range inputs with `EMLError`. - Financial methods that expose `ADecimals` now apply it consistently. NPV rounds only its final result, and amortization schedules use the requested precision for payment amounts. - Undefined financial ratios now raise `EFinanceError` when a required denominator is zero instead of returning a fabricated zero. - `FinanceLib.Bonds` and `FinanceLib.NPV` remain lightweight focused entry units and now export directly nameable supporting aliases for their cash-flow and amortization types. - Random-producing library functions no longer call `Randomize` internally. - The test runner installs `cthreads` first on Unix and verbose algebra-test output is opt-in through `MATHLIB_TEST_VERBOSE`. - The Lazarus package version is now 1.2.0 and includes the shared engineering exception unit. - The Lazarus package and registration unit are now named `mathlib_fp` to match the mathlib-fp project name. - Lazarus 4.8 is the minimum supported Lazarus version; CI validates the package against that baseline. - `EngineeringLib.Signal.TDoubleArray` now aliases the shared `MathBase.SharedTypes.TDoubleArray` type. - `TFluidDynamicsKit.PumpHead` now accepts explicit inlet and outlet velocities and implements the Bernoulli velocity-head term `(v2²-v1²)/(2g)`. - General-purpose statistics and geometry sorts now use O(n log n) algorithms instead of quadratic insertion sorts. - Root finders expose detailed convergence records, iterative matrix and scalar solvers report exhaustion explicitly, PCA records per-component iterations, and linear programming exposes a precise termination status. - Linear regression now uses centered Householder QR instead of normal equations, improving behavior for high-offset and ill-scaled data. ### Fixed - Fixed example 11's unsupported format specifier and duplicate polynomial intercept, which previously caused a singular regression system. - Unknown unit names no longer silently default to length. Non-`Try` APIs raise `EUnitConversionError`; `Try...` APIs retain their `False` contract. - Significant-digit formatting now uses stable round-half-to-even behavior on both Win32 extended-precision and Win64 targets. - Fixed `InternalRateOfReturn`, which previously returned its initial 10% guess without iterating. It now brackets and bisects positive or negative rates and reports invalid or unbracketable cash-flow inputs with `EFinanceError`. - Corrected FinanceLib signatures, result-type scope, numeric examples, and exception contracts in the API guide and source comments. - Corrected odd-order high-pass and band-stop FIR centre indexing, added safe FFT/IFFT empty and mismatched-array handling, and documented the complete N-bin spectral outputs. - Humidity-ratio and adiabatic calculations now reject invalid pressure and specific-heat-ratio domains with `EThermodynamicsError`. - Engineering comments and API documentation now cover focused aliases, formula domains, signal shapes, every UnitConversion public API, exact unit names, fixed-duration time conventions, and locale-sensitive parsing. - Removed all compiler warnings from clean normal and UTF-8 builds. - Fixed broken source links, stale API names, version text, and random/bootstrap contracts across the documentation. - Corrected matrix inverse permutation handling, LU row swaps, scale-relative rank/singularity decisions, exact triangular cleanup, and large-norm matrix exponentials, including architecture-independent overflow reporting. - Corrected forward ray-circle semantics, polygon-boundary classification, non-negative radius validation, and zero-vector angle handling. - Corrected exact small-sample Mann-Whitney p-values, K-S D/p-value semantics, Shapiro-Wilk normal scores, and pooled-variance Cohen's d. - Corrected FFT period-bin mapping and ARIMA MA/integration forecasts. - Added checked combinatorics overflow paths and overflow-safe modular exponentiation, a Win32-safe sieve index path, plus stable hyperbolic and hypotenuse calculations. - Strengthened finite-value, dimension, domain, and callback validation across numerical, optimization, time-series, matrix, geometry, and ML entry points. --- ## [1.1.0] - 2026-04-16 ### Added #### NumericsLib — new library (`src/NumericsLib.Numerics.pas`, class `TNumericsKit`) A complete numerical methods library with no external dependencies. ##### Root Finding - `Bisection` — guaranteed bracketed convergence; raises `EInvalidArgument` when f(a)·f(b) ≥ 0 - `NewtonRaphson` — fast quadratic convergence using the function and its derivative - `Brent` — hybrid method combining bisection, secant, and inverse-quadratic interpolation; the recommended general-purpose solver - `Secant` — derivative-free quasi-Newton method requiring two initial guesses ##### Numerical Integration (Quadrature) - `TrapezoidalRule` — composite trapezoidal rule; O(h²) accuracy - `SimpsonRule` — composite Simpson's rule; O(h⁴) accuracy; auto-increments odd N to even - `GaussLegendre5` — 5-point Gauss-Legendre quadrature; exact for polynomials up to degree 9 ##### ODE Solvers (dy/dt = f(t, y)) - `EulerStep` / `EulerSolve` — 1st-order explicit Euler method - `RK4Step` / `RK4Solve` — classic 4th-order Runge-Kutta; local error O(h⁵) - Both solvers return a `TODESolution` record with aligned `T` and `Y` arrays ##### Interpolation - `LinearInterp` — piecewise linear with binary-search interval lookup; clamps at endpoints - `LagrangeInterp` — global Lagrange polynomial through all knots - `CubicSplineBuild` / `CubicSplineEval` — natural cubic spline solved via the Thomas tridiagonal algorithm; exact at every knot ##### NumericsLib test coverage 39 new tests in `tests/TestNumericsLib.pas` verify analytically known results: `√2`, the Dottie number, `∫x³ dx = 0.25`, exponential ODE exact solution, harmonic oscillator, and spline exactness at knots. #### EngineeringLib.Signal — FFT and FIR filter design (replacing stubs) ##### FFT (Cooley-Tukey radix-2 DIT) - `FFT(var RealPart, ImagPart; Inverse)` — in-place FFT/IFFT; length must be a power of 2 - `CalculateFFT` — real input → complex spectrum; auto-pads to next power of 2 - `CalculateIFFT` — complex spectrum → real signal - `CalculateFFTMagnitudePhase` — complete N-bin magnitude and phase spectra ##### FIR Filter Design (windowed-sinc) - `DesignFIRLowPass(CutoffFreq, Order, WindowType)` — normalised cutoff in (0, 0.5) - `DesignFIRHighPass(CutoffFreq, Order, WindowType)` — spectral inversion of low-pass - `DesignFIRBandPass(LowCutoff, HighCutoff, Order, WindowType)` — difference of two low-pass filters - `DesignFIRBandStop(LowCutoff, HighCutoff, Order, WindowType)` — notch/band-reject filter - `ApplyFIRFilter(Signal, Coeffs)` — direct-form convolution; output length = N + M − 1 All FIR designs produce symmetric (linear-phase) coefficients. Low-pass is normalised to unit DC gain; high-pass and band-stop use spectral inversion. ##### Signal test coverage `tests/TestEngineeringLib_Signal.pas` expanded from 11 to 52 tests covering FFT linearity, Parseval's theorem, round-trip IFFT accuracy, DC/Nyquist correctness, FIR coefficient symmetry, and `ApplyFIRFilter` impulse response. ### Changed - `EngineeringLib.Signal` — `CalculateFFT` and `CalculateFFTMagnitudePhase` were stubs that raised `Exception` unconditionally; both are now fully implemented. - `tests/TestRunner.lpr` — `TestNumericsLib` registered alongside the existing test suites. --- ## [1.0.1] - 2026-04-16 ### Fixed - `AlgebraLib.Matrices` — `TMatrixKit.IsPositiveDefinite` previously used an insufficient check (determinant > 0 and positive diagonal elements). It now attempts a Cholesky factorisation; success is the definitive test for symmetric positive definite matrices. - `AlgebraLib.Matrices` — `TMatrixKit.IsPositiveSemidefinite` had the same flaw. It now computes all eigenvalues via `EigenDecomposition` and checks that none are less than −1e-9. - `AlgebraLib.Matrices` — `TMatrixKit.Cholesky` previously called `IsPositiveDefinite` as a pre-check, creating a circular dependency after the above fix. The guard is now an inline check: if the diagonal term under the square root is negative, `EMatrixError` is raised immediately. ### Performance - `AlgebraLib.Matrices` — `TMatrixKit.Determinant` replaced recursive cofactor expansion (O(n!)) with LU-based calculation (O(n³)). - `AlgebraLib.Matrices` — `BLOCK_SIZE` increased from 4 to 64 for better L1 cache utilisation. - `AlgebraLib.Matrices` — `TMatrixKit.Multiply` now spawns parallel worker threads for matrices with 64 or more rows. --- ## [1.0.0] - 2026-04-14 ### Changed - The math modules (`TStatsKit`, `TFinanceKit`, `TMatrixKit`, `TTrigKit`, and supporting units) have been separated from [tidykit-fp](https://github.com/ikelaiah/tidykit-fp) into this standalone monorepo. - Source reorganised into focused sub-libraries: `MathBase`, `AlgebraLib`, `FinanceLib`, `EngineeringLib`, and `StatsLib`, each with its own `README.md`. - Unit namespaces updated to match the new library structure (e.g. `MathBase.SharedTypes`, `AlgebraLib.Matrices`, `StatsLib.Stats`). - `EngineeringLib` expanded with `EngineeringLib.FluidDynamics`, `EngineeringLib.Thermodynamics`, `EngineeringLib.Signal`, and `EngineeringLib.UnitConversion`. - `MathBase` expanded with `MathBase.Trigonometry`. ### Removed - All non-math modules (Strings, FS, DateTime, JSON, Logger, Request, Crypto, Archive) are no longer part of this repository; they remain in tidykit-fp. --- ## [0.1.5] - 2025-04-21 (tidykit-fp era) ### Added - Ubuntu 24.04.02 compatibility for DateTime and FS modules. - Automatic test environment detection for the HTTP request module. - HTTP fallback mechanism for testing HTTPS endpoints when OpenSSL is unavailable. - Cross-platform SSL/TLS initialisation support for HTTP requests. ### Fixed - File timestamp handling issues on Unix systems. - Path normalisation for cross-platform compatibility. - OpenSSL initialisation and error handling on Linux systems. --- ## [0.1.0] - 2025-03-13 (tidykit-fp era — initial release) ### Added - `TStatsKit` — statistical calculations. - `TFinanceKit` — financial mathematics. - `TMatrixKit` — matrix operations with decompositions. - `TTrigKit` — trigonometric functions. - JSON operations, logging, cryptography (SHA3, SHA2, AES-256), archive, HTTP client.