Random Light Travel Time Network Generator

Description

Generate fictional 3D locations and symmetric distance and vacuum light-time matrices using an explicit kilometers-per-unit conversion.

A physical-model fixture draws inputs under explicit units and delegates a stated idealized calculation. Computed values follow that model; they are separate from measurements, calibration, and environmental effects omitted by the assumptions.

Generate fictional 3D locations and symmetric distance and vacuum light-time matrices using an explicit kilometers-per-unit conversion.

When to use this tool

Use this generator to create reproducible light travel time network cases from the supplied model or bank. Inspect the returned evidence before using cases in a test or exercise.

How to use the tool and how it works

Supply locationCount, x, y, z, coordinateUnit, kilometersPerUnit in the field shapes below. Set seed when you need an explicit replay.
Run the tool and correct any input error. For generated controls, distinguish a successful fixture containing an invalid case from failure to generate the fixture.
Read coordinateUnit, kilometersPerUnit, locations, distanceUnits, distanceKilometers, lightTimeSeconds, lightTimeDays. Use the conventions below and keep answer-bearing fields separate when presenting an exercise.

Draw Cartesian locations in a caller-declared coordinate unit, compute symmetric Euclidean distances, convert using kilometersPerUnit, and delegate light travel time in seconds and days for every unordered pair.^[1]

Delegated operations used for this result: light travel time. Their calculation or parsing conventions apply to the corresponding result fields.^[2]

Input field	Meaning and units	Accepted input
locationCount	Location Count	Required. Safe integer; minimum 1; maximum 32.
x	X	Required. Object; no unknown keys.
x.minimum	Minimum	Required. Finite number.
x.maximum	Maximum	Required. Finite number.
y	Y	Required. Object; no unknown keys.
y.minimum	Minimum	Required. Finite number.
y.maximum	Maximum	Required. Finite number.
z	Z	Required. Object; no unknown keys.
z.minimum	Minimum	Required. Finite number.
z.maximum	Maximum	Required. Finite number.
coordinateUnit	Coordinate Unit	Required. Text; minimum UTF-16 length 1; maximum UTF-16 length 64.
kilometersPerUnit	Kilometers Per Unit	Required. Finite number; strictly above 0.
seed	Optional numeric seed; takes precedence over context randomness. Without either, use the fixed tool.io default seed.	Optional. Safe integer.

Output field	Interpretation	Returned shape
coordinateUnit	Coordinate Unit	Required. Text; minimum UTF-16 length 1; maximum UTF-16 length 64.
kilometersPerUnit	Kilometers Per Unit	Required. Finite number; strictly above 0.
locations	Locations	Required. Array of Object; no unknown keys.; minimum items 1; maximum items 32.
locations[].id	Literal identifier used to match records, independently of their display labels.	Required. Safe integer; minimum 0; maximum 31.
locations[].x	X	Required. Finite number.
locations[].y	Y	Required. Finite number.
locations[].z	Z	Required. Finite number.
distanceUnits	Distance Units	Required. Array of Array of Finite number; minimum 0.; minimum items 1; maximum items 32.; minimum items 1; maximum items 32.
distanceKilometers	Distance Kilometers	Required. Array of Array of Finite number; minimum 0.; minimum items 1; maximum items 32.; minimum items 1; maximum items 32.
lightTimeSeconds	Light Time Seconds	Required. Array of Array of Finite number; minimum 0.; minimum items 1; maximum items 32.; minimum items 1; maximum items 32.
lightTimeDays	Light Time Days	Required. Array of Array of Finite number; minimum 0.; minimum items 1; maximum items 32.; minimum items 1; maximum items 32.
randomness	Replay metadata: source is seed or context; seed is the normalized 32-bit seed or null for a context source.	Required. Object; no unknown keys.
randomness.seed	Optional numeric replay seed; normalization and precedence are explained below.	Required. Safe integer. or Null.
randomness.source	Source	Required. Text; one of "context", "seed".

An explicit safe-integer seed takes precedence over injected context randomness and is normalized to an unsigned 32-bit integer. With no seed and no context source, replay uses the fixed tool.io default seed. A context source must return finite values from zero inclusive to one exclusive; its advancing state must be retained separately. randomness records the source and normalized seed, or null for context. These generators are not cryptographic random sources.

json

{
  "input": {
    "locationCount": 2,
    "x": {
      "minimum": 0,
      "maximum": 10
    },
    "y": {
      "minimum": 0,
      "maximum": 0
    },
    "z": {
      "minimum": 0,
      "maximum": 0
    },
    "coordinateUnit": "light-second",
    "kilometersPerUnit": 299792.458,
    "seed": 42
  },
  "output": {
    "coordinateUnit": "light-second",
    "kilometersPerUnit": 299792.458,
    "locations": [
      {
        "id": 0,
        "x": 6.011037519201636,
        "y": 0,
        "z": 0
      },
      {
        "id": 1,
        "x": 6.697340414393693,
        "y": 0,
        "z": 0
      }
    ],
    "distanceUnits": [
      [
        0,
        0.6863028951920569
      ],
      [
        0.6863028951920569,
        0
      ]
    ],
    "distanceKilometers": [
      [
        0,
        205748.4318821431
      ],
      [
        205748.4318821431,
        0
      ]
    ],
    "lightTimeSeconds": [
      [
        0,
        0.6863028951920569
      ],
      [
        0.6863028951920569,
        0
      ]
    ],
    "lightTimeDays": [
      [
        0,
        0.000007943320546204362
      ],
      [
        0.000007943320546204362,
        0
      ]
    ],
    "randomness": {
      "seed": 42,
      "source": "seed"
    }
  }
}

Limitations and assumptions

Diagonal entries are zero. The scale is supplied rather than inferred from coordinateUnit. The model assumes straight-line vacuum propagation and omits motion, gravity, routing, and communication processing delays.
A replay requires the same complete input and implementation. Randomized construction does not guarantee uniform coverage of every feasible output; finite samples can repeat unless a distinct-selection rule is explicitly stated.
The field tables state structural bounds; cross-field constraints and bounded search or output budgets also apply. Unknown keys are rejected where the object contract disallows them. Input errors are distinct from null fields and deliberate invalid controls in a successful output.

Alternative or Complementary methods

For a supplied example, inspect the returned construction or delegated check directly. To evaluate a consumer, also test cases chosen for its own boundaries; a generated finite corpus does not establish exhaustive coverage.

References

Tool behavior and example: Random Light Travel Time Network Generator — tool.io
Calculation or validation: astronomy/light-travel-time — tool.io

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