# units pack

8 nodes, in `noodlelab` and above.

## Units

(node-units.constant)=
### Constant

`units.constant`

A named constant: π, the speed of light, standard gravity... with
its unit, and with its CODATA uncertainty when it was measured rather than
defined. Exact constants without a unit are plain numbers; use unit '1' to
feed one into Quantity Math. One node can feed many others: two nodes
naming the same measured constant are sampled independently by Monte Carlo.
Symbolic Values take constants by name too (a line 'g = g0').

**Inputs**

| Name | Type | Description |
|---|---|---|
| `name` | `str` | A built-in constant, one from the workspace's constants.toml, or one of the graph's own (Constants panel) Default `'pi'`. |
| `unit` | `str` | Express it in this unit; empty: as defined. '1' makes a plain number such as π a dimensionless quantity, for Quantity Math Default `''`. |

**Outputs**

| Name | Type | Description |
|---|---|---|
| `result` | `Any` |  |

(node-units.convert_units)=
### Convert Units

`units.convert_units`

Express a quantity in another unit of the same dimension. Links do this
by themselves; use the node to choose the unit a result is shown in.

**Inputs**

| Name | Type | Description |
|---|---|---|
| `quantity` | `Quantity` |  |
| `unit` | `str` | Default `'m'`. |

**Outputs**

| Name | Type | Description |
|---|---|---|
| `result` | `Quantity` |  |

(node-units.magnitude)=
### Magnitude

`units.magnitude`

The number without its unit, in ``unit`` (empty: the quantity's own).
For array quantities, use Magnitude (Array).

**Inputs**

| Name | Type | Description |
|---|---|---|
| `quantity` | `Quantity` |  |
| `unit` | `str` | Default `''`. |

**Outputs**

| Name | Type | Description |
|---|---|---|
| `result` | `float` |  |

(node-units.magnitude_array)=
### Magnitude (Array)

`units.magnitude_array`

The numbers of an array quantity without the unit, in ``unit``
(empty: the quantity's own): floats, or complex numbers when the
quantity holds them.

**Inputs**

| Name | Type | Description |
|---|---|---|
| `quantity` | `Quantity` |  |
| `unit` | `str` | Default `''`. |

**Outputs**

| Name | Type | Description |
|---|---|---|
| `result` | `NDArray` |  |

(node-units.make_quantity)=
### Make Quantity

`units.make_quantity`

Attach a unit to a plain number.

**Inputs**

| Name | Type | Description |
|---|---|---|
| `value` | `float` |  |
| `unit` | `str` | Default `'m'`. |

**Outputs**

| Name | Type | Description |
|---|---|---|
| `result` | `Quantity` |  |

(node-units.make_quantity_array)=
### Make Quantity (Array)

`units.make_quantity_array`

Attach a unit to an array of numbers, such as a table column.

**Inputs**

| Name | Type | Description |
|---|---|---|
| `values` | `NDArray[floating]` |  |
| `unit` | `str` | Default `'m'`. |

**Outputs**

| Name | Type | Description |
|---|---|---|
| `result` | `Quantity` |  |

(node-units.quantity)=
### Quantity

`units.quantity`

A constant with a unit, typed as text: 9.81 m/s^2, 3 km, 25 degC.

**Inputs**

| Name | Type | Description |
|---|---|---|
| `value` | `Quantity` | Default `'1.0 m'`. |

**Outputs**

| Name | Type | Description |
|---|---|---|
| `result` | `Quantity` |  |

(node-units.quantity_math)=
### Quantity Math

`units.quantity_math`

Arithmetic on quantities. Add, subtract, minimum, maximum and modulo
need the same dimension; the result is in the first input's unit. A
temperature plus or minus a difference (delta_degC) is a temperature, and
one temperature minus another is a difference. Power
raises A to B and root takes the B-th root of A: B is a plain number, and
must be exact when A has a unit, because the result's unit depends on it.
Sqrt, absolute and negate ignore B.

**Inputs**

| Name | Type | Description |
|---|---|---|
| `a` | `Quantity` |  |
| `b` | `Quantity` | Default `'1.0'`. |
| `operation` | `Literal['add', 'subtract', 'multiply', 'divide', 'power', 'root', 'minimum', 'maximum', 'modulo', 'sqrt', 'absolute', 'negate']` | Default `'multiply'`. |

**Outputs**

| Name | Type | Description |
|---|---|---|
| `result` | `Quantity` |  |