UnitNumbers

A C# library to work with numbers with unit.

Documentation

Types:

Dimension:

This is a struct to store the dimension of a number. For example feet, meter, and mile all are of the length dimension type. Area(km^2, m^2, and ...) has the dimension of Length^2. The Length parameter of the Dimension struct shows the power of the length dimension:

feet, meter, mile, ... -> Dimension.Length=1

square feet, square meter, square mile, ... -> Dimension.Length=2

This struct has 7 properties(for seven base units). These properties are: Mass,Length,Time,Temperature,Current,Mole, and Luminosity. They are all initialized to 0.

Dimensions:

A struct containing static properties for easier initialization of dimensions. For example instead of this:

new Dimension(){Length=3, Time=-1};//flow rate dimension

you can use:

Dimensions.FlowRate;

Unit:

This type represent a unit. e.g. ft, meter, ... To create a new unit:

var hour = new Unit("hr", Dimensions.Time, 3600.0, 0.0);

UnitNumber:

This type represent the actual number with unit. e.g. 1 ft

Getting started

Defining a new unit:

The constructor is:

public Unit(string identifier, Dimension dimension, double multiplier, double sum = 0.0)

• Identifier: an identifier for the unit for example cm for centimeter
• Dimension: Dimension of the unit: for example Length=1 (Length) for meter and Length=2 (Length^2) for square meter(area)
• multiplier: to what number should this unit multiplied to convert it to the SI unit. for example cm should be multiplied to 0.01 to convert it to meter(which is SI standard unit for length) 1cm=0.01m
• sum: What number should be added to this unit to convert it to the SI unit. for example we should add 273.15 to °C to convert it to Kelvin(which is SI standard unit for temperature)

// defining the foot(ft) unit. It is of the Length type. And one foot equals
// 0.3048 m (meter is the SI unit for length) 
Unit ft = new Unit("ft", Dimensions.Length, 0.3048);
// defining the Centigrade(C) unit. It is of the temperature type. And K = 1*C + 273.15
Unit c = new Unit("C", Dimensions.Temperature, 1,273.15);
// defining the Farenheit(F) unit. It is of the temperature type. And K = 5.0/9.0*F + (273.15-32.0/1.8)
Unit f = new Unit("F", Dimensions.Temperature, 5.0/9.0,273.15-32.0/1.8);

You can also define units by multiplying and dividing other units, or raising them to some powers:

Unit ft = new Unit("ft", Dimensions.Length, 0.3048);
Unit min = new Unit("min", Dimension.Time, 60.0);
Unit ft2 = ft*ft; //defining square foot
Unit ft3 = ft.Pow(3);//defining cubic foot
Unit CFM = ft3/min;

Basic units created by constructor are called Basic units. You can find out if a unit is basic by IsBasic property. This property returns true for basic units and false for units that are created using mathematical notations. This is important for units that have offset from each others. For example C^2/C has the temperature^1 dimension. K^2/K also has the temperature dimension, but C^2/C should be converted to K^2/K using following formula:

1 C^2/C = 1 K^2/K

not the 1 C^2/C +273.15 = 1 K^2/K. IsBasic provides a way to distinguish between C^2/C and C.

Unit conversion:

suppose we defined these units:

Unit ft = new Unit("ft", Dimensions.Length, 0.3048);
Unit ft2 = ft*ft; //defining square foot
Unit ft3 = ft.Pow(3);//defining cubic foot
Unit cm = new Unit("cm", Dimensions.Length, 0.01);
Unit cm2 = cm.Pow(2);
Unit cm3 = cm.Pow(3);

You can convert from and to SI units(of the same dimension) using unit itself:

double l1 = ft.FromSI(1.2);//1.2 meter to feet
double a1 = cm2.ToSI(5.6);//5.6cm^2 to meter^2

if you have a unit number you can get its value in any other unit as long as they have the same dimensions:

var n1 = new UnitNumber(1.2,ft);
var n2 = new UnitNumber(5.4,cm2);
double d1 = n1.GetValue(cm);//getting n1 in cm unit
double d1 = n1.GetValue(cm2);//Error: An error is thrown! because dimensions wont match.

Evaluating expressions:

This library can be used to evaluate mathematical expressions involving units. For this, we need to create a CalculationEngine instance first:

using UnitConversionNS;
using UnitConversionNS.ExpressionParsing;
UnitsCore core = new UnitsCore();//to hold information about units and the way they can be converted to each other
//adding some units to core
core.RegisterUnit(new Unit("m", Dimensions.Length, 1.0));
core.RegisterUnit(new Unit("cm", Dimensions.Length, 0.01));
CalculationEngine engine = new CalculationEngine(core);

then we can pass the mathematical expression(in form of a string) to the Calculate method in the engine:

using UnitConversionNS.ExpressionParsing.Execution;//ExecutionResult is defined here
ExecutionResult result = engine.Calculate("(1[m]+3[cm])/2");
//result.DataType -> DataType.UnitNumber
//(UnitNumber)reslut.Value -> 0.515[m]

Result is reported in the whaterever unit whith apears first([m] in this case). You can change that by calling ExecutionResult ChangeUnit(Unit unit). This will give you another ExecutionResult with the requested unit.