# observation toy.region_probe

Describes the entry `toy.region_probe` at version `0.1.0`, registered by `mime.testing.toys._entries.ToyRegionProbe`.

## At a glance

- observation `toy.region_probe`, version `0.1.0`, namespace `toy`
- Nodes: [`ToyRegionProbeNode`](../../nodes/ToyRegionProbeNode.md)
- Undocumented, so with no equations to link: [`ToyRegionProbeNode`](../../nodes/ToyRegionProbeNode.md)
- Derivative: `exact`
- Validity: none declared

## What it models, and when not to use it

No hand-written part: this entry's source has not been written (the docs walk counts it).

## Settings

| Setting | Type | Default | Dimension | Role | Default's kind |
|---|---|---|---|---|---|
| `body` | `Any` | `null` | none | none declared | none: required |
| `medium` | `Any` | `null` | none | none declared | none: required |
| `rate` | `Quantity \| None` | `null` | none | numerical | convention |

Each role and default's kind is the entry's `setting_roles` (`mime.registry.SettingRole`); a setting that declares none is required.

Each default is a claim (`mime.registry.DefaultKind`): a determined default is resolved in every profile, a convention taken in every profile, a numerical default taken in exploratory only and stamped pending. Their rules and bases:

- `rate` (convention): the setting's written default; an observation reads every base step unless the experiment chooses a slower rate

## Roles, reads and deliveries

Roles, bound by keyword when the entry is attached: `body` (body), `medium` (medium).

Reads:

| Label | Reads |
|---|---|
| `position` | body [`toy.body.position`](../../vocabulary.md#namespace-toy) |

## Nodes it builds

- [`ToyRegionProbeNode`](../../nodes/ToyRegionProbeNode.md)

Declared in `builds`; the node walk compares it with what a round-trip case builds.

## Gradient status

The derivative through this entry is `exact`, the derivative of what it computes.

## Outputs

What a run's result reads by name, with its units (`result[handle].<output>`). A per-step output is a series, with its time axis, when the run records it (`run(..., record=[handle.<output>])`); an output at the end is reduced by the graph and always there, over its window. A window holds the steps whose end lies after its start and not after its end.

| Output | When | Dimension | Unit | Shape | What it is | Reduced from |
|---|---|---|---|---|---|---|
| `distance` | per step | length (m) | `m` | `()` | the region's signed distance at the body's position, each step |  |
| `normal` | per step | dimensionless | `1` | `(3,)` | the region's outward normal there, each step |  |
| `nearest` | per step | length (m) | `m` | `(3,)` | the region's nearest point to the body's position, each step |  |

## Validity

none declared

## References

none declared

## Other declarations

| Class variable | Type | Value |
|---|---|---|
| `id_roles` | `ClassVar[tuple[str, ...] \| None]` | `["body", "medium"]` |
| `moving` | `ClassVar[bool]` | `false` |