# interaction toy.spring

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

## At a glance

- interaction `toy.spring`, version `0.1.0`, namespace `toy`
- Nodes: [`ToySpringNode`](../../nodes/ToySpringNode.md)
- Undocumented, so with no equations to link: [`ToySpringNode`](../../nodes/ToySpringNode.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 |
|---|---|---|---|---|---|
| `k` | `Annotated[Quantity, Force / Length]` | `{"unit": "kg s^-2", "value": 1.7}` | kg s^-2 | none declared | none: required |
| `x0` | `Annotated[Quantity, Length]` | `{"unit": "m", "value": [0.05, -0.02, 0.01]}` | length (m) | none declared | none: required |

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

## Roles, reads and deliveries

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

Reads:

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

Delivers:

| Label | Role | Into the target |
|---|---|---|
| `load` | body | [`toy.body.load`](../../mechanisms/load.md) |

## Nodes it builds

- [`ToySpringNode`](../../nodes/ToySpringNode.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.

## Validity

none declared

## References

none declared

## Other declarations

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