Calculation Methodology
Structured workflow for engineering calculation documents. Covers phases 1-5
(authoring); phase 6 hands off to calculation-report for rendering.
6-Phase Workflow
| Phase | Name | Gate | Output |
|---|
| 1 | Problem Definition | Scope, objective, and limitations stated | Sections 01-02 populated |
| 2 | Input Gathering | All inputs sourced, units verified | Sections 03-06 populated |
| 3 | Method Selection | Standard identified, applicability confirmed | Section 07 populated |
| 4 | Computation | Step-by-step calc with clause refs | Sections 08-09 populated |
| 5 | Validation | Independent check or benchmark completed | Sections 10-13 populated |
| 6 | Reporting | Trigger calculation-report skill | Sections 14-16, final output |
Section Reference Table
Each section has a dedicated reference file in sections/ with purpose, schema
fields, required content, quality checklist, example snippet, and common mistakes.
| # | Section | Reference File | Phase | Required |
|---|
| 01 | Metadata | 01-metadata.md | 1 | Yes |
| 02 | Scope | 02-scope.md | 1 | Yes |
| 03 | Design Basis | 03-design-basis.md | 2 | Yes |
| 04 | Materials | 04-materials.md | 2 | Conditional |
| 05 | Inputs | 05-inputs.md | 2 | Yes |
| 06 | Assumptions | 06-assumptions.md | 2 | Yes |
| 07 | Methodology | 07-methodology.md | 3 | Yes |
| 08 | Calculations | 08-calculations.md | 4 | Yes |
| 09 | Outputs | 09-outputs.md | 4 | Yes |
| 10 | Sensitivity | 10-sensitivity.md | 5 | Recommended |
| 11 | Validation | 11-validation.md | 5 | Yes |
| 12 | Verification | 12-verification.md | 5 | Yes |
| 13 | Conclusions | 13-conclusions.md | 5 | Yes |
| 14 | Charts | 14-charts.md | 6 | Recommended |
| 15 | Data Tables | 15-data-tables.md | 6 | Recommended |
| 16 | References | 16-references.md | 6 | Yes |
Phase-to-Section Mapping
Phase 1 — Problem Definition
Populate sections 01 (Metadata) and 02 (Scope). Establish document control,
define the calculation objective, and bound the scope with explicit inclusions,
exclusions, and validity ranges. No computation occurs in this phase.
Phase 2 — Input Gathering
Populate sections 03 (Design Basis), 04 (Materials), 05 (Inputs), and
06 (Assumptions). Every input must have a traceable source. Material properties
must reference certificates or code tables. Assumptions must state whether they
are conservative or best-estimate and justify why.
Phase 3 — Method Selection
Populate section 07 (Methodology). Select the governing standard and edition.
Confirm applicability to the problem geometry, load regime, and material.
Present equations in symbolic form before substituting numeric values.
Phase 4 — Computation
Populate sections 08 (Calculations) and 09 (Outputs). Execute the method
step-by-step with clause references at each step. Record intermediate results
with units. Summarize results with pass/fail status and utilization ratios.
Phase 5 — Validation
Populate sections 10 (Sensitivity), 11 (Validation), 12 (Verification), and
13 (Conclusions). Perform sensitivity sweeps on key parameters. Validate
against benchmarks or alternative methods. Record independent check details.
State the adequacy conclusion with governing check identification.
Phase 6 — Reporting
Populate sections 14 (Charts), 15 (Data Tables), and 16 (References).
Finalize visualizations and citation list. Then trigger the calculation-report
skill to render the structured YAML into HTML/PDF output.
Handoff to calculation-report:
# After all sections are populated:
# 1. Validate YAML structure against schema
# 2. Invoke calculation-report skill with the calc YAML path
# 3. Review rendered output for formatting issues
Quality Checklist — Commonly Missed Items
These items are the most frequent causes of calculation rejection in
engineering review, drawn from EFCOG, DNV, Structures Centre, and Caltrans
guidance:
Problem Definition (Phase 1)
Input Gathering (Phase 2)
Method Selection (Phase 3)
Computation (Phase 4)
Validation (Phase 5)
Reporting (Phase 6)
Plan-Review Placeholder Artifacts
When the user asks for an engineering-calculation concept artifact before implementation approval, create a clearly labeled placeholder HTML under the plan/review artifact area (for example docs/plans/assets/<issue>-<topic>-placeholder.html) rather than final output folders. The placeholder should demonstrate reviewer-facing chart intent — chart titles, axis labels with units, dropdown/default behavior, formulas, assumptions, sign/frame conventions, and limitations — while explicitly stating it is not the TDD-backed final deliverable. Link it from the GitHub issue and the issue plan artifact map, commit/push it transactionally, and verify with both a static HTML structure check and a browser/console load check when possible.
Usage
# Typical invocation pattern:
# 1. Agent loads this skill when a calculation task is identified
# 2. Work through phases 1-5, populating section YAML
# 3. At phase 6, hand off to calculation-report for rendering
#
# For section-specific guidance, read the relevant file:
# .claude/skills/engineering/calculation-methodology/sections/01-metadata.md
Research Sources
This skill synthesizes calculation documentation best practices from:
- EFCOG (Energy Facility Contractors Group) — calculation note guidance
- DNV (Det Norske Veritas) — recommended practices for documentation
- Structures Centre — structural calculation note templates
- Eng-Tips — practitioner discussions on calculation quality
- Caltrans — bridge design calculation documentation standards
