Source: https://guthlabs.ai/docs/instruments/vis-viva-equation-solver/implementation/

instrument implementation / implementation-contract

# Vis-Viva Equation Solver implementation

A source-bound implementation contract for Vis-Viva Equation Solver; 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**: t4-185

**Effect**: Computation or source lookup only

## Input and validation requirements

The specification provides no explicit input validation for r=0 or for a negative square-root radicand. Such inputs produce undefined results and must be rejected. The output also lacks a stated sign convention, so it cannot distinguish velocity direction from speed magnitude.

## 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": {
    "GM_km3_s2": 398600,
    "r_km": 7000,
    "a_km": 7000
  },
  "expected_outputs": {
    "velocity_km_s": 7.5460491
  },
  "working": "v² = 398600 × (2/7000 - 1/7000) = 398600 × (1/7000) = 56.9428571 km²/s². v = sqrt(56.9428571) = 7.5460491 km/s."
}
````

## Other records

[01**Overview**](<https://guthlabs.ai/docs/instruments/vis-viva-equation-solver/>)[02**Mechanism**](<https://guthlabs.ai/docs/instruments/vis-viva-equation-solver/mechanism/>)[04**Qualification**](<https://guthlabs.ai/docs/instruments/vis-viva-equation-solver/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`