# Just.PreciseMath

**WIP — repository scaffolding only; no library implementation or tests yet.**

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 empty test project currently reports no tests (MTP exit code 8); this is not a
passing test suite. Once tests exist, add `--coverlet` to the test command for
coverage. 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.