MaterialNest

Formula methodology

Formula changelog

Current calculator versions, compatibility rules, and the evidence required before a formula change ships.

Transparent variables, rounding decisions, and scope limits for every result.

Last reviewed: July 18, 2026

Domain-expert review: pending

This changelog records formula behavior that can change a saved result. Copy, layout, or diagram-only edits do not require a formula-version change unless they also alter calculation behavior.

Current formula versions

  • Baluster spacing 1.0.0: equal-end-gap count and spacing formula.
  • Railing posts 2.0.0: section geometry, shared endpoints, per-section openings, and per-run post spacing.
  • Deck railing 3.0.0: section-aware unspliced rail cuts, deterministic offcut reuse, actual post-to-post clear rail length, distinct top/bottom stock, and a waste-based whole-piece minimum.
  • Fence posts 2.0.0: layout topology, shared endpoints, individual gate placement, and per-run spacing.
  • Chain-link fence 2.0.0: shared fence geometry, gate deductions, bottom wire, independent gate prices, and optional concrete integration.
  • Post concrete 1.1.0: round or rectangular post displacement plus explicit net and waste outputs.

Change classification

A patch version is for a correction that preserves the documented input meaning and materially equivalent output. A minor version adds backward-compatible input or output behavior. A major version changes input semantics, topology, rounding order, or quantities in a way that can make a saved result incompatible.

Saved items must never be silently recalculated. A compatibility registry classifies a transition as compatible or review-required. Compatible stale items may offer explicit recalculation. Review-required items retain their prior input and output until the user completes the current validated form.

Deck railing 2.0.0 to 3.0.0

Version 2.0.0 pooled total run length and could undercount stock when rails must terminate at every post. Version 3.0.0 derives each clear post-to-post cut, reuses only offcuts that hold a complete cut, and rejects stock shorter than a required span. The input shape remains compatible, but quantities can change. Saved 2.0.0 output is preserved as stale and is replaced only after explicit recalculation.

Release checklist

Every formula change must update all of the following in the same verified batch:

  1. Formula version and compatibility classification.
  2. Unit, equivalence, boundary, invalid-input, rounding, reconciliation, and golden tests affected by the change.
  3. Solved-example fixtures and manual derivations where outputs change.
  4. Relevant methodology variables, unit rules, waste rules, edge cases, references, and review date.
  5. This changelog and the saved-project migration/recalculation behavior.

Expected golden values must be authored independently from the production function. Comparable-calculator evidence must record the exact input, output, access date, and explained differences. A source link alone is not a completed comparison.

Review status

The July 17, 2026 evidence set contains 30 manually checked numerical examples—five per calculator. Automated golden tests compare the engines with those fixed expected values. Comparable tools and authoritative context sources are recorded in the methodology pages, but formal comparable-calculator execution and qualified domain-expert review remain pending and must not be represented as complete.