### 10 unstable releases (4 breaking)

0.5.1 | Jun 8, 2022 |
---|---|

0.5.0 | Mar 9, 2022 |

0.4.1 | Jan 10, 2022 |

0.4.0 | Dec 16, 2021 |

0.1.1 | Jul 9, 2021 |

#**60** in Science

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**MIT/Apache**

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# quantity

Representation of quantities, i.e. of unit valued scalars and arrays. Rust library with Python bindings.

As opposed to other implementations, this crate does not attempt to achieve compile time checks on units. It is written with flexibility in mind and is able to represent arbitrarily complex units. Additional to simple scalar quantities, it also provides utilities for vector valued quantities, based on the ndarray crate, where all entries share the same unit.

## Installation and Usage

### Rust

Add this to your

:`Cargo .toml`

`[``dependencies``]`
`quantity ``=` `"`0.5`"`

## Python package

Python bindings for the SI functionalities are published under the name si-units on PyPI.

## Examples

Calculate pressure of an ideal gas.

`let` temperature `=` `25.``0` `*` `CELSIUS``;`
`let` volume `=` `1.``5` `*` `METER``.``powi``(``3``)``;`
`let` moles `=` `75.``0` `*` `MOL``;`
`let` pressure `=` moles `*` `RGAS` `*` temperature `/` volume`;`
`println!``(``"``{:.5}``"``,` pressure`)``;` `//` 123.94785 kPa

Calculate the gravitational pull of the moon on the earth.

`let` mass_earth `=` `5.``9724e24` `*` `KILOGRAM``;`
`let` mass_moon `=` `7.``346e22` `*` `KILOGRAM``;`
`let` distance `=` `383.``398` `*` `KILO` `*` `METER``;`
`let` force `=` G `*` mass_earth `*` mass_moon `/` distance`.``powi``(``2``)``;`
`println!``(``"``{:.5e}``"``,` force`)``;` `//` 1.99208e26 N

Calculate the pressure distribution in the atmosphere using the barometric formula.

`let` z `=` `SIArray1``::`linspace`(``1.``0` `*` `METER``,` `70.``0` `*` `KILO` `*` `METER``,` `10``)``?``;`
`let` g `=` `9.``81` `*` `METER` `/` `SECOND``.``powi``(``2``)``;`
`let` m `=` `28.``949` `*` `GRAM` `/` `MOL``;`
`let` t `=` `10.``0` `*` `CELSIUS``;`
`let` p0 `=` `BAR``;`
`let` pressure `=` p0 `*` `(``-``&`z `*` m `*` g`)``.``to_reduced``(``RGAS` `*` t`)``?``.``mapv``(``f64``::`exp`)``;`
`for` i `in` `0``..``10` `{`
`println!``(``"`z = `{:8.5}` p = `{:9.5}``"``,` z`.``get``(`i`)``,` pressure`.``get``(`i`)``)``;`
`}`
`//` z = 1.00000 m p = 99.98794 kPa
`//` z = 7.77867 km p = 39.12796 kPa
`//` z = 15.55633 km p = 15.31182 kPa
`//` z = 23.33400 km p = 5.99192 kPa
`//` z = 31.11167 km p = 2.34480 kPa
`//` z = 38.88933 km p = 917.58301 Pa
`//` z = 46.66700 km p = 359.07479 Pa
`//` z = 54.44467 km p = 140.51557 Pa
`//` z = 62.22233 km p = 54.98750 Pa
`//` z = 70.00000 km p = 21.51808 Pa

## Documentation

For the rust documentation, see here.

For the python documentation, see here.

## Development

To build the project including the bindings to python, we use maturin.

When developing, use

`maturin develop ``-``-`release `-`m si`-`units`/`Cargo`.`toml

To build the python wheels, use

`maturin build ``-``-`release `-`m si`-`units`/`Cargo`.`toml

To build the documentation you need

and some additional packages. From the root directory, type`sphinx`

`cd`` si-units/docs`
`make`` html`

To run the doctests, from the root directory, type

`cd`` si-units/docs`
`make`` doctest`

#### Dependencies

~2.8–8.5MB

~169K SLoC