Source: https://guthlabs.ai/docs/instruments/center-of-mass-calculator/implementation/

instrument implementation / implementation-contract

# Center of Mass Calculator implementation

A source-bound implementation contract for Center of Mass Calculator; deployment and executable qualification remain separate.

Status: **VERIFIED_CLEAN**Lifecycle: **implementation-contract**

## 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**: t4-239

**Effect**: Computation or source lookup only

## Input and validation requirements

The all-zero-mass input makes the denominator vanish and the result undefined. Because the specification does not state validation behavior, a plain arithmetic implementation could emit NaN instead of rejecting the input. The formula also has no actual piecewise branch, so the branch-switch requirement is not applicable beyond confirming that the same formula is used.

## 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": {
    "masses_positions": [
      {
        "mass": 2,
        "position": [
          0,
          0
        ]
      },
      {
        "mass": 3,
        "position": [
          5,
          0
        ]
      }
    ],
    "mass_unit": "kg",
    "position_unit": "m"
  },
  "expected_outputs": {
    "r_cm": [
      3,
      0
    ],
    "position_unit": "m"
  },
  "working": "Total mass = 2 + 3 = 5 kg.\\nX numerator = (2×0) + (3×5) = 0 + 15 = 15 kg·m.\\nY numerator = (2×0) + (3×0) = 0 + 0 = 0 kg·m.\\nCOM = (15/5, 0/5) = (3, 0) m."
}
````

## Other records

[01**Overview**](<https://guthlabs.ai/docs/instruments/center-of-mass-calculator/>)[02**Mechanism**](<https://guthlabs.ai/docs/instruments/center-of-mass-calculator/mechanism/>)[04**Qualification**](<https://guthlabs.ai/docs/instruments/center-of-mass-calculator/qualification/>)

## Sources and evidence

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

- `VERIFIED_LEDGER.json`

- `evidence-tranche4/tranche4-results.json`