Source: https://guthlabs.ai/docs/instruments/spherical-mirror-equation-calculator/implementation/

instrument implementation / implementation-contract

# Spherical Mirror Equation Calculator implementation

A source-bound implementation contract for Spherical Mirror Equation 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**: t5-123

**Effect**: Computation or source lookup only

## Input and validation requirements

The specification admits zero-radius and do=f inputs that produce undefined results, and it leaves the sign convention for convex mirrors implicit. An implementation that performs plain arithmetic without validation or explicit sign-convention handling can return division-by-zero errors or physically incorrect image results.

## 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": {
    "mirror_type": "concave",
    "R": "40 cm",
    "object_distance": "60 cm",
    "sign_convention": "real-is-positive"
  },
  "expected_outputs": {
    "f": "20 cm",
    "di": "30 cm",
    "m": -0.5,
    "image_characteristics": "real, inverted, diminished"
  },
  "working": "f=R/2=40/2=20 cm. 1/di=1/f−1/do=1/20−1/60=3/60−1/60=2/60=1/30 cm⁻¹, so di=30 cm. m=−di/do=−30/60=−1/2=−0.5. Since di>0, the image is real; since m<0, it is inverted; since |m|<1, it is diminished."
}
````

## Other records

[01**Overview**](<https://guthlabs.ai/docs/instruments/spherical-mirror-equation-calculator/>)[02**Mechanism**](<https://guthlabs.ai/docs/instruments/spherical-mirror-equation-calculator/mechanism/>)[04**Qualification**](<https://guthlabs.ai/docs/instruments/spherical-mirror-equation-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-tranche5/tranche5-results.json`