Perpetuity Value 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

t2-032

Effect

Computation or source lookup only

Input and validation requirements

The instrument has an undefined-result failure when g equals r: the growing-perpetuity denominator r-g becomes zero. It also must reject the broader invalid region g > r, where the infinite stream does not converge. Ambiguous rate units and cash-flow signs can produce materially different outputs if conventions are not specified.

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": {
    "mode": "level",
    "PMT": 1000,
    "rate": 0.05
  },
  "expected_outputs": {
    "PV": 20000
  },
  "working": "PV=PMT/r=1000/0.05=1000/(5/100)=1000*20=20000."
}

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-tranche2/tranche2-results.json