perf: reduce checked determinant query overhead

[acgetchell]

• Aggregate D≥5 range proofs before a single cold scaled replay.
• Preserve immediate small-dimension fallback and range-safe determinant behavior.

Closes #190

Summary by CodeRabbit

• Bug Fixes

  • Improved determinant calculations for LU and LDLT decompositions, especially for matrices with very small or large values.
  • Enhanced handling of numerical range limits to help preserve accurate results across different matrix sizes.

• Refactor

  • Streamlined internal product and scaling result handling without changing the public API.

• Chores

  • Updated the pinned formatting and validation tool version.

[coderabbitai]

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ℹ️ Recent review info

⚙️ Run configuration

Configuration used: Path: .coderabbit.yaml

Review profile: CHILL

Plan: Pro

Run ID: 2eb7d41c-fe1c-47fa-b495-e835f2b1174a

📥 Commits

Reviewing files that changed from the base of the PR and between 32e67d4 and 2bdf1d3.

📒 Files selected for processing (4)

• justfile
• src/ldlt.rs
• src/lu.rs
• src/scaled_product.rs

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📝 Walkthrough

Walkthrough

The change replaces the range-check enum with a product-plus-proof struct. LU and LDLT determinant paths use the new accessors and dimension-specific fallback behavior. The Justfile updates the pinned rumdl version.

Changes

Determinant range safety

Layer / File(s)	Summary
Range-check result contract src/scaled_product.rs	RangeCheckedProduct now stores the product and range-preservation status. Accessors and tests cover normal, underflow, overflow, and boundary cases.
LU and LDLT determinant consumers src/lu.rs, src/ldlt.rs	Lu::det and Ldlt::det consume the new result API. Small dimensions fall back immediately on range loss; larger dimensions defer the fallback until accumulation completes.

Tooling pin

Layer / File(s)	Summary
rumdl version pin justfile	The pinned rumdl version changes from 0.2.52 to 0.2.53.

Estimated code review effort: 3 (Moderate) | ~20 minutes

Sequence Diagram(s)

sequenceDiagram
  participant LuDet as Lu::det
  participant LdltDet as Ldlt::det
  participant RangeCheck as range_checked_product
  participant Scaled as ScaledProduct
  LuDet->>RangeCheck: multiply accumulator and factor
  RangeCheck-->>LuDet: product and range_preserved
  LdltDet->>RangeCheck: multiply accumulator and factor
  RangeCheck-->>LdltDet: product and range_preserved
  LuDet->>Scaled: use scaled accumulation after unsafe result
  LdltDet->>Scaled: use scaled accumulation after unsafe result

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Possibly related PRs

• acgetchell/la-stack#34: Modifies determinant computation through the Matrix::det path.
• acgetchell/la-stack#181: Modifies small-dimension determinant and range handling.
• acgetchell/la-stack#182: Modifies determinant overflow and range-safety logic.

Suggested labels: performance, rust

🚥 Pre-merge checks | ✅ 3 | ❌ 2

❌ Failed checks (1 warning, 1 inconclusive)

Check name	Status	Explanation	Resolution
Out of Scope Changes check	⚠️ Warning	The Justfile rumdl version update is unrelated to the determinant performance objectives in issue #190.	Remove the rumdl pin update or move it to a separate pull request with its own justification.
Linked Issues check	❓ Inconclusive	The Rust changes match the linked determinant optimization and preserve the described small-dimension fallback and range-proof behavior, but benchmark evidence is not provided.	Provide same-command profiling, benchmark, and correctness results required by issue #190 before merge.

✅ Passed checks (3 passed)

Check name	Status	Explanation
Description Check	✅ Passed	Check skipped - CodeRabbit’s high-level summary is enabled.
Title check	✅ Passed	The title clearly identifies the determinant performance optimization and reduced checked-query overhead.
Docstring Coverage	✅ Passed	No functions found in the changed files to evaluate docstring coverage. Skipping docstring coverage check.

✨ Finishing Touches

📝 Generate docstrings

• Create stacked PR
• Commit on current branch

🧪 Generate unit tests (beta)

• Create PR with unit tests
• Commit unit tests in branch perf/190-determinant-throughput

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[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 97.86%. Comparing base (32e67d4) to head (2bdf1d3).
✅ All tests successful. No failed tests found.

Additional details and impacted files

@@            Coverage Diff             @@
##             main     #209      +/-   ##
==========================================
- Coverage   97.86%   97.86%   -0.01%     
==========================================
  Files           8        8              
  Lines        4975     5007      +32     
==========================================
+ Hits         4869     4900      +31     
- Misses        106      107       +1     

Flag	Coverage Δ
unittests	97.86% <100.00%> (-0.01%)	⬇️

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