Wentworth Grain-Size Classifier implementation

Binding contract

This record describes what an executable surface must bind and validate. It does not claim that a public calculator, package, or production route is deployed.

Record owner

Guth Instruments

Lifecycle

verified-clean

Evidence ID

t7-103

Effect

Computation or source lookup only

Input and validation requirements

The zero-diameter input produces an undefined logarithm and must be rejected. The specification also does not explicitly define exact class-boundary endpoint ownership or enforce the diameter unit, creating boundary and unit-convention failure risks.

Required corrections

No binding erratum is attached to this unique-name record. Implementers must still preserve the declared units, domain, and failure behavior.

Inspectable interface fixture

The sample below is evidence for interface and validation tests, not a production implementation.

{
  "inputs": {
    "grain_diameter": 1,
    "unit": "mm"
  },
  "expected_outputs": {
    "phi": 0,
    "class_name": "very coarse sand"
  },
  "reference_data": {
    "rows": [
      {
        "diameter_mm": 1,
        "phi_boundary": 0,
        "class_name": "very coarse sand",
        "source_convention": "Udden-Wentworth grain-size scale, widely tabulated standard value"
      },
      {
        "diameter_mm": 2,
        "phi_boundary": -1,
        "class_name": "granule",
        "source_convention": "Udden-Wentworth grain-size scale, widely tabulated standard value"
      }
    ],
    "boundary_convention": "[lower diameter, upper diameter)"
  },
  "working": "φ = -log2(1.0) = -log2(1) = 0.0. The diameter is at the 1.0 mm boundary and, using [lower, upper), belongs to the 1–2 mm very coarse sand interval."
}

Other records

Sources and evidence

These pointers bind the page to evidence. They do not grant authority or collapse verification into deployment.

• VERIFIED_LEDGER.json
• evidence-tranche7/tranche7-results.json