Source: https://guthlabs.ai/docs/instruments/mach-number-calculator/

instrument / verified-clean

# Mach Number Calculator

The current ledger marks this instrument verified clean within the source-bound verification corpus.

Status: **VERIFIED_CLEAN**Lifecycle: **verified-clean**

## Inspectable records

[01**Overview**Purpose and lifecycle](<https://guthlabs.ai/docs/instruments/mach-number-calculator/>)[02**Mechanism**Method and assumptions](<https://guthlabs.ai/docs/instruments/mach-number-calculator/mechanism/>)[03**Implementation**Binding and validation](<https://guthlabs.ai/docs/instruments/mach-number-calculator/implementation/>)[04**Qualification**Evidence and errata](<https://guthlabs.ai/docs/instruments/mach-number-calculator/qualification/>)

## Ledger state

The current ledger marks this instrument verified clean within the source-bound verification corpus.

**Area**: Thermodynamics, Fluids & Aero

**Tranche**: tranche-5

**Evidence ID**: t5-044

**Ledger rows**: 1

No ledger note is attached.

## Review findings

The mathematical formulas pass standard ideal-gas compressible-flow verification, but the specification needs review because γ, R, unit handling, ISA implementation, altitude definition, temperature precedence, valid ranges, and honest labeling are unspecified.

### Formula and scope findings

- The formulas M=V/a and a=√(γRT) are standard and correct for Mach number and ideal-gas speed of sound, but γ and R are not specified in the instrument spec.

- Altitude-based temperature is underspecified: the ISA table, altitude reference, atmospheric layer rules, and valid altitude range are not defined.

- The input declaration "altitude or T" does not specify how the calculator selects or validates temperature when both are supplied, nor whether altitude is geometric or geopotential.

### Unit assumptions

- Velocity V and speed of sound a must use the same units; test vectors use m/s unless explicitly stated otherwise.

- For the SI calculations, γ=1.4 for air and R=287.05 J/(kg·K).

- T is static absolute temperature in kelvin, not Celsius or Fahrenheit.

- Altitude-based temperatures use the International Standard Atmosphere (ISA): T=288.15−0.0065h for the troposphere up to 11,000 m, with h in meters.

- The knot conversion used is 1 kt=0.514444 m/s.

## Boundary hardening

**BREAK_CLAIMED** · SELF_FLAGGED

A zero-temperature input makes the speed of sound zero and the Mach-number denominator vanish; the instrument must reject it instead of exposing a JavaScript Infinity or undefined result. The altitude-based ISA calculation also requires an unstated table/branch convention at 11000 m, and signed velocity creates an explicit Mach-sign convention ambiguity.

## Errata and corrections

No applied erratum is attached to this unique-name record.

## Inspectable example

4 review vectors are recorded. One source-bound sample is shown below.

````
{
  "inputs": {
    "velocity": 170.1461435,
    "velocity_unit": "m/s",
    "temperature": 288.15,
    "temperature_unit": "K",
    "gamma": 1.4,
    "R": 287.05
  },
  "expected_outputs": {
    "mach_number": 0.5,
    "speed_of_sound_m_per_s": 340.2923
  },
  "working": "a=√(γRT)=√(1.4×287.05×288.15)=√115798.8405=340.2923 m/s. M=V/a=170.1461435/340.2923=0.5000."
}
````

## Related workflows

No source-defined multi-instrument workflow membership is recorded.

## Sources and evidence

These pointers bind the page to evidence. They do not grant authority or collapse verification into deployment.

- `VERIFIED_LEDGER.json · VERIFIED_CLEAN`

- `evidence-tranche5/tranche5-results.json`

- `BOUNDARY_HAZARD_CATALOG.json`