Source: https://guthlabs.ai/docs/instruments/cents-pitch-deviation-calculator/implementation/

instrument implementation / implementation-contract

# Cents / Pitch Deviation Calculator implementation

A source-bound implementation contract for Cents / Pitch Deviation 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**: t4-121

**Effect**: Computation or source lookup only

## Input and validation requirements

The formula produces undefined results for zero frequencies, but the specification does not state positive-frequency validation or rejection behavior. It also leaves the sign/order convention to the interface beyond the formula notation, creating a plausible +1200 versus -1200 interpretation.

## 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": {
    "f1": 440,
    "f2": 440,
    "unit": "Hz"
  },
  "expected_outputs": {
    "cents": 0
  },
  "working": "f1/f2 = 440/440 = 1. log2(1) = 0. cents = 1200 × 0 = 0 cents."
}
````

## Other records

[01**Overview**](<https://guthlabs.ai/docs/instruments/cents-pitch-deviation-calculator/>)[02**Mechanism**](<https://guthlabs.ai/docs/instruments/cents-pitch-deviation-calculator/mechanism/>)[04**Qualification**](<https://guthlabs.ai/docs/instruments/cents-pitch-deviation-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`