# Just.PreciseMath

**WIP — initial library implementation and one smoke test; numerical correctness is not yet validated.**

A .NET 10 library being developed for extended-precision floating-point arithmetic
using double-double representations (a high/low pair of `double` values), with
common mathematical functions. This is fixed extended precision, not arbitrary
precision; accuracy guarantees and the public API are not settled.

## Planned scope

- Double-double arithmetic, constants, comparisons, conversions, and formatting.
- Common functions including `Abs`, `Sqrt`, `Pow`, `Exp`, and `Log`.
- Correctness tests against higher-precision references and performance benchmarks.

The [consolidated legacy review](review-legacy/Review-Revisited-DoubleDouble.md)
is the starting point. Priorities are normalization and special-value contracts
(NaN, infinities, signed zero), corrected constants and scalar subtraction,
consistent comparisons, precision-preserving conversions/formatting, and
range-safe arithmetic and transcendental functions, including cancellation and
subnormal cases. The files in `review-legacy/` contain known defects: they are
reference material only, are not compiled, and should not be used in production.

## Layout

- `0-source/Just.PreciseMath/` — library and package metadata.
- `1-tests/Just.PreciseMath.Tests/` — xUnit v3, Shouldly, and MTP-native Coverlet.
- `2-benchmarks/Just.PreciseMath.Benchmarks/` — BenchmarkDotNet scaffold.
- `review-legacy/` — original implementation and numerical reviews.

## Development

Use the .NET 10 SDK selected by `global.json` (10.0.1xx, latest installed patch).
Shared settings enable nullable analysis, .NET 10 recommended analyzers, build-time
code-style checks, and warnings as errors. `.editorconfig` retains advisory style
preferences alongside explicitly enforced warning/error rules.

```sh
dotnet restore Just.PreciseMath.slnx
dotnet build Just.PreciseMath.slnx -c Release --no-restore
dotnet test --solution Just.PreciseMath.slnx -c Release --no-build
dotnet format Just.PreciseMath.slnx --verify-no-changes --no-restore
```

The initial smoke test checks that `DoubleDouble.One` exposes high and low
components of `1.0` and `0.0`. It exercises the test/coverage pipeline, not the
numerical accuracy of the planned library.

CI collects TRX test results and Cobertura coverage for `Just.PreciseMath` only,
excluding test dependencies, and requires at least one test. The `test-results`
artifact contains TRX test results and timestamped Cobertura XML coverage reports,
retained for three days.
Open the workflow run in Gitea Actions and download that artifact. Upload is
attempted even when tests fail; no badges or repository-write token are needed.

To generate the same reports locally:

```sh
dotnet test --solution Just.PreciseMath.slnx -c Release --no-build --minimum-expected-tests 1 --report-xunit-trx --coverlet --coverlet-output-format cobertura --coverlet-include "[Just.PreciseMath]*"
```

Reports are written under each test project's `bin/Release/net10.0/TestResults/`.
The benchmark project deliberately builds as a library without source files;
add an entry point and benchmark cases, then change `OutputType` to `Exe` and run
it in Release without a debugger. No performance results exist yet.

Package metadata uses the development version `0.1.0-dev`. Licensed under the
[MIT License](LICENSE), included in the package.
Do not publish this scaffold as a usable numerical library.