ROI Calculator 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

t4-140

Effect

Computation or source lookup only

Input and validation requirements

An initial cost of zero makes the ROI denominator vanish, producing an undefined result. The specification does not state an input-validation rule, so the calculator must explicitly reject this case rather than emit Infinity or NaN.

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": {
    "initial_cost": 1000,
    "final_value": 1200,
    "holding_period_years": 2
  },
  "expected_outputs": {
    "roi_percent": 20,
    "annualized_roi_percent": 9.544511501
  },
  "working": "ROI=(1200-1000)/1000=200/1000=0.20=20%. Annualized ROI=(1+0.20)^(1/2)-1=1.20^0.5-1=1.095445115-1=0.095445115=9.544511501%."
}

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-tranche4/tranche4-results.json