Units

This crate provides typed physical quantities for the rest of qitech_lib. It is a custom uom unit system: the seven SI base quantities, a hand-picked set of derived quantities, and only the units QiTech machines actually use. The storage type is always f64.

Other crates use it wherever a value has a physical meaning. For example, ethercat_hal analog I/O returns ElectricCurrent / ElectricPotential, and xtrem returns weights as Mass.

Usage

use units::f64::{Length, Time, Velocity, ElectricCurrent};
use units::length::millimeter;
use units::time::second;
use units::velocity::meter_per_minute;
use units::electric_current::milliampere;

let d = Length::new::<millimeter>(1500.0);
let t = Time::new::<second>(3.0);
let v: Velocity = d / t;                          // dimensions are checked at compile time
println!("{:.1} m/min", v.get::<meter_per_minute>());   // 30.0

let i = ElectricCurrent::new::<milliampere>(12.0);

• Quantity types live in units::f64::*, which is also re-exported at the crate root, so units::Mass works.
• Unit markers live in the module named after the quantity (units::mass::gram).
• Construct and read values with Q::new::<unit>(x) and q.get::<unit>().
• Arithmetic between quantities gives the correctly-dimensioned result type.
• units::ConstZero is re-exported from uom, so you can write Length::ZERO.

Quantities and units

Only the units listed here exist. This crate does not include all of uom's units, so, for example, there is no minute for Time and no millisecond.

Quantity (units::f64::…)	Module	Units
Length	length	millimeter, centimeter, meter
Mass	mass	gram, kilogram, pound, ounce
Time	time	second
ElectricCurrent	electric_current	milliampere, centiampere, ampere
ThermodynamicTemperature	thermodynamic_temperature	kelvin, degree_celsius
AmountOfSubstance	amount_of_substance	mole
LuminousIntensity	luminous_intensity	candela
Velocity	velocity	millimeter_per_second, meter_per_second, meter_per_minute
Acceleration	acceleration	meter_per_second_squared, meter_per_minute_per_second
Jerk	jerk	meter_per_second_cubed, meter_per_minute_per_second_squared
Angle ¹	angle	radian, degree, revolution
AngularVelocity ¹	angular_velocity	radian_per_second, degree_per_second, revolution_per_second, revolution_per_minute
AngularAcceleration ¹	angular_acceleration	radian_per_second_squared, degree_per_second_squared, revolution_per_minute_per_second
AngularJerk ¹	angular_jerk	radian_per_second_cubed, degree_per_second_cubed, revolution_per_minute_per_second_squared
ElectricPotential	electric_potential	millivolt, centivolt, volt
Power	power	milliwatt, watt, kilowatt
Energy	energy	joule, watt_hour, kilowatt_hour
Frequency	frequency	millihertz, centihertz, hertz, cycle_per_minute
Pressure	pressure	pascal, bar
VolumeRate	volume_rate	cubic_meter_per_second, liter_per_second, liter_per_minute
Ratio	ratio	ratio

¹ The angular quantities have the kind dyn AngleKind. They are dimensionless like Ratio, but the kind keeps them from being mixed with plain ratios or frequencies by accident.

Adding a unit or quantity

• New unit for an existing quantity: add an @unit_name: factor; "symbol", "singular", "plural"; line to the units { … } block in that quantity's file, for example src/volume_rate.rs. factor converts to the base SI unit.
• New quantity:
  1. Create src/<quantity>.rs with a quantity! { … } block that gives its ISQ dimension exponents. Copy an existing file.
  2. Register it in the units: U { … } list of system! in src/lib.rs.