the first optimization round

README.md

@@ -133,7 +133,7 @@ bool success = DoubleDouble.TryParse("1.25e-2".AsSpan(), CultureInfo.InvariantCu
 
 The planned `PreciseMath` static class and its `Abs`, `Sqrt`, `Pow`, `Exp`, and
 `Log` functions are not implemented. Generic-math interfaces beyond `ISignedNumber`,
-additional text formats/general round-trip formatting, and broader performance
+additional text formats/general round-trip formatting, and non-arithmetic performance
 benchmarks remain deferred.
 Replacing allocating arithmetic boundary fallbacks is also deferred; the current
 `BigInteger` paths remain in place. That optimization does not require removing
@@ -156,18 +156,9 @@ on CI workflow runs.
 
 ## Benchmarks
 
-The BenchmarkDotNet suite compares same-type `+`, `-`, `*`, and `/` operations for
-`DoubleDouble`, `decimal`, and `double`: 12 methods with two input cases each.
-Each operation/input group uses `double` as its baseline and reports allocations.
-Operands are stored in fields and results are returned to the harness; conversions
-and construction happen in setup, outside the timed methods.
-
-The left inputs are `1.25` (binary-exact) and `1.1` (a nonzero low component in
-`DoubleDouble`); the right input is `0.75`. Decimal and double-double inputs originate
-from the same decimal values, while `double` rounds to binary64. These types have
-different precision and range contracts: this is a cost comparison, not an accuracy
-test. Exceptional values, exponent-boundary fallbacks, mixed-type operators,
-conversions, parsing, and formatting are not benchmarked yet.
+BenchmarkDotNet measures arithmetic throughput, dependent-chain latency, and allocations,
+including comparisons of `DoubleDouble`, `decimal`, and `double`, mixed scalar operations,
+and exponent-boundary paths. These are performance measurements, not accuracy tests.
 
 After the Release build above, run from the repository root:
 
@@ -175,19 +166,16 @@ After the Release build above, run from the repository root:
 # Discover benchmark methods without running them.
 dotnet run --project 2-benchmarks/Just.PreciseMath.Benchmarks -c Release --no-build -- --list flat
 
-# Quick execution check (also run in CI); not useful for timing comparisons.
+# Smoke test; Dry timings are not performance measurements.
 dotnet run --project 2-benchmarks/Just.PreciseMath.Benchmarks -c Release --no-build -- --job Dry --filter '*'
 
-# Full measurement run; optionally select an operation with --anyCategories Addition.
+# Full measurement run.
 dotnet run --project 2-benchmarks/Just.PreciseMath.Benchmarks -c Release --no-build -- --filter '*'
 ```
 
 Reports are written under the ignored `BenchmarkDotNet.Artifacts/` directory.
-Empty selections and failed benchmark runs return a nonzero exit code. CI only
-checks execution, with no performance gate. Use full runs on an idle, controlled
-machine for comparisons; a scalar `double` operation may approach harness overhead,
-so inspect BenchmarkDotNet warnings before interpreting ratios. Do not compare
-coverage-instrumented runs or treat Dry-job timings as performance measurements.
+Replace `'*'` with a benchmark-name pattern to select a subset; use `--artifacts <path>`
+to keep runs separate. Run measurements on an idle machine and inspect BenchmarkDotNet warnings.
 
 ## Project structure