Durwella.Measurements

Utilities for using measurements with units. Measurement dimensions are easily constructed from existing dimensions, and new dimensions of measurements with new units can be added. Dimensions are tracked through operations - e.g. a length divided by a time yields a velocity.

Using Existing Dimensions

Note: All "Units" are defined as UnitOfMeasurements with a value of 1.0 - e.g. Units.Meters is really a UnitOfMeasurement object with value 1. In the code, using Unit = Measurements.UnitOfMeasurement; is often used so that units can be defined sightly more naturally.

Below is an example of using the existing units to calculate hydrostatic pressure in psi.

UnitOfMeasurement g   = 9.80665 * Units.MetersPerSecondSquared;
UnitOfMeasurement rho = 1000 * Units.KilogramsPerCubicMeter;
UnitOfMeasurement h   = 10000 * Units.Feet;

UnitOfMeasurement pressure = rho * g * h;

Console.WriteLine(pressure.Type.Name + " = " + pressure.ToString(Units.PoundsPerSquareInch);

> Pressure = 4335.28 psi

The dimension of the resulting pressure is detected automatically by keeping track of the UnitOfMeasurements tracked through the operations.

Note that units can be combined arbitrarily by multiplication and division. The following code is equivalent to above:

UnitOfMeasurement g   = 9.80665 * Units.Meters / (Units.Seconds * Units.Seconds);
UnitOfMeasurement rho = 1000 * Units.Kilograms / (Units.Meters * (Units.Meters * Units.Meters));
UnitOfMeasurement h   = 10000 * Units.Feet;

UnitOfMeasurement pressure = rho * g * h;

Console.WriteLine(pressure.Type.Name + " = " + pressure.ToString(Units.PoundsPerSquareInch);

Note: Determination of unit labels is imperfect at the moment. If Console.WriteLine(pressure.ToString(Units.Pounds / (Units.Inches * Units.Inches))); were used instead, the resulting output would be Pressure = 4335.28 lb/in in. A named unit should be used for output if a specific resulting label is desired.

Defining New Dimensions and Units

The user isn't restricted to the built-in dimensions and units. Consider a new domain: cookie baking.

A baker needs to bake 12 gross cookies (1 gross = 144 cookies) by the end of the week. If he wants to get all of the baking done in a standard 40-hour work week, at what rate must be bake cookies?

// Define new dimensions: a cookie count, which is a base dimension, and a cookie rate, which is a compound dimension using the cookie count and time.
var cookieCount = new Dimension("Cookie Count");
var cookieRate = new Dimension("Cookie Rate", cookieCount / Dimensions.Time);

// Define some cookie units, including specifying the unit to be considered the default SI unit
var cookies = cookieCount.NewSIUnit("cookies");
var dozenCookies = new UnitOfMeasurement("dz", 12 * cookies);
var grossCookies = new UnitOfMeasurement("gr", 144 * cookies);

// Define a new time unit (for this application, workWeek = 40 * Units.Hours would work just as well)
var workWeek = new UnitOfMeasurement("work week", 40 * Units.Hours);

// The baker needs to bake 12 gross cookies
var totalCookies = 12 * grossCookies;
// rate = count / time
var cookiesRate =  totalCookies / workWeek;

Console.WriteLine(cookiesRate.ToString("{0:0.000} {1}"));
Console.WriteLine(cookiesRate.ToString(cookies / Units.Minutes));
Console.WriteLine(cookiesRate.ToString("{0:0.0} {1}", dozenCookies / Units.Hours));

> 0.012 cookies/s
> 0.72 cookies/min
> 3.6 dz/hr

Note that the cookieRate variable is unused (and unnecessary). Because the rate is defined in terms of the base units (namely cookieCount and Dimensions.Time) which have SI units defined, the SI units for cookieRate are defined implicitly. A definition for the SI unit of cookieRate is only required if a specific label (e.g. cps) is desired instead of the automatically-generated cookies/s.