Source: https://guthlabs.ai/docs/instruments/half-life-calculator-multi-order/implementation/

instrument implementation / implementation-contract

# Half-Life Calculator (multi-order) implementation

A source-bound implementation contract for Half-Life Calculator (multi-order); 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**: t4-287

**Effect**: Computation or source lookup only

## Input and validation requirements

The specification admits inputs that produce division by zero or physically invalid negative half-lives, and it does not define validation behavior for zero or negative rate constants. It also does not explicitly define handling of an order value at or between formula branches.

## 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": {
    "order": "zero",
    "k": 0.02,
    "k_unit": "mol L^-1 s^-1",
    "A0": 0.1,
    "A0_unit": "mol L^-1"
  },
  "expected_outputs": {
    "t_half": 2.5,
    "t_unit": "s"
  },
  "working": "t½ = [A]0/(2k) = 0.100 mol L^-1 / (2 × 0.020 mol L^-1 s^-1) = 0.100 / 0.040 s = 2.50 s."
}
````

## Other records

[01**Overview**](<https://guthlabs.ai/docs/instruments/half-life-calculator-multi-order/>)[02**Mechanism**](<https://guthlabs.ai/docs/instruments/half-life-calculator-multi-order/mechanism/>)[04**Qualification**](<https://guthlabs.ai/docs/instruments/half-life-calculator-multi-order/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`