Source: https://guthlabs.ai/docs/instruments/isentropic-flow-relations-calculator/implementation/

instrument implementation / implementation-contract

# Isentropic Flow Relations Calculator implementation

A source-bound implementation contract for Isentropic Flow Relations 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**: t5-076

**Effect**: Computation or source lookup only

## Input and validation requirements

M=0 causes division by zero in A/A*, and a signed negative Mach produces a nonphysical negative area ratio unless the instrument explicitly uses Mach magnitude or rejects signed inputs.

## 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": {
    "Mach": 1,
    "gamma": 1.4
  },
  "expected_outputs": {
    "T_over_T0": 0.8333333333,
    "P_over_P0": 0.5282817877,
    "rho_over_rho0": 0.6339381452,
    "A_over_Astar": 1
  },
  "working": "For γ=1.4, (γ−1)/2=0.2, γ/(γ−1)=3.5, 1/(γ−1)=2.5, and (γ+1)/(2(γ−1))=3. First q=1+0.2(1²)=1.2. T/T0=1/1.2=0.8333333333. P/P0=1.2^(-3.5)=0.5282817877. ρ/ρ0=1.2^(-2.5)=0.6339381452. A/A*=(1/1)[(2/2.4)(1.2)]^3=1[(5/6)(1.2)]^3=1^3=1. This is the sonic throat boundary case M=1."
}
````

## Other records

[01**Overview**](<https://guthlabs.ai/docs/instruments/isentropic-flow-relations-calculator/>)[02**Mechanism**](<https://guthlabs.ai/docs/instruments/isentropic-flow-relations-calculator/mechanism/>)[04**Qualification**](<https://guthlabs.ai/docs/instruments/isentropic-flow-relations-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`