Room Modes Calculator (Axial) 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

t2-049

Effect

Computation or source lookup only

Input and validation requirements

The specification exposes an undefined result for a zero room dimension and ambiguity around zero-order, non-axial, and signed mode-order inputs. A robust implementation must validate positive dimensions, handle the all-zero mode explicitly, and enforce or clearly flag the axial-only selection rule.

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": {
    "room_length": 5,
    "room_width": 4,
    "room_height": 2.5,
    "dimension_unit": "m",
    "speed_of_sound": 343,
    "axial_modes": {
      "x": [
        1,
        2,
        3
      ],
      "y": [
        1,
        2,
        3
      ],
      "z": [
        1,
        2,
        3
      ]
    }
  },
  "expected_outputs": {
    "frequencies_hz": [
      {
        "mode": [
          1,
          0,
          0
        ],
        "frequency": 34.3
      },
      {
        "mode": [
          2,
          0,
          0
        ],
        "frequency": 68.6
      },
      {
        "mode": [
          3,
          0,
          0
        ],
        "frequency": 102.9
      },
      {
        "mode": [
          0,
          1,
          0
        ],
        "frequency": 42.875
      },
      {
        "mode": [
          0,
          2,
          0
        ],
        "frequency": 85.75
      },
      {
        "mode": [
          0,
          3,
          0
        ],
        "frequency": 128.625
      },
      {
        "mode": [
          0,
          0,
          1
        ],
        "frequency": 68.6
      },
      {
        "mode": [
          0,
          0,
          2
        ],
        "frequency": 137.2
      },
      {
        "mode": [
          0,
          0,
          3
        ],
        "frequency": 205.8
      }
    ],
    "mode_overlap_warnings": [
      {
        "modes": [
          [
            2,
            0,
            0
          ],
          [
            0,
            0,
            1
          ]
        ],
        "frequency_hz": 68.6,
        "reason": "exact frequency match"
      }
    ]
  },
  "working": "c/2 = 343/2 = 171.5. Length-axis base: 171.5/5 = 34.3 Hz, so orders 1,2,3 give 34.3, 2*34.3 = 68.6, and 3*34.3 = 102.9 Hz. Width-axis base: 171.5/4 = 42.875 Hz, so orders 1,2,3 give 42.875, 2*42.875 = 85.75, and 3*42.875 = 128.625 Hz. Height-axis base: 171.5/2.5 = 68.6 Hz, so orders 1,2,3 give 68.6, 2*68.6 = 137.2, and 3*68.6 = 205.8 Hz. The length-axis second mode and height-axis first mode both equal 68.6 Hz."
}

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-tranche2/tranche2-results.json