Dimensions class

The Dimensions class represents the dimensions of a physical quantity.

The Seven Base Quantities

In the International System of Units (SI) all quantities are considered to be either one of the seven base quantities (Length, Mass, Time Interval, Temperature, Current, Intensity and Amount of Substance) or derived from those base quantities through combinations and/or arbitrary exponents. The Dimensions of a quantity capture which combination applies for that particular quantity. Any combination of these base quantities is possible; in practice less than 100 derived quantities are in common use. The Dimensions of a quantity determine its type and directly relate to that quantity's significance and meaning in the real world.

The Dimensions Class Also Tracks Angle and Solid Angle

The dimensions that are tracked include the seven base SI quantities and also the angle and solid angle dimensionless quantities. Angular quantities are often distinguished from their non-angular counterparts even if the SI base dimensions are equal. Consequently, in order to support such differentiation, Angle and SolidAngle dimensions are stored alongside the base seven dimensions and used to distinguish between dimensions and determine quantity types. To test whether two Dimensions objects are equal strictly in terms of the base SI dimensions, the equalsSI method may be used.

Constructors

Dimensions()

No-arg constructor sets all dimensions to zero (that is, a scalar quantity).

Dimensions.constant(Map<String, num> dims, {Type? qType})

Constructs a constant Dimensions object with a map of base dimension keys to exponents

const

Dimensions.copy(Dimensions d2, {bool includeTypeHint = true})

Creates a Dimensions object by copying an existing Dimensions object.

Dimensions.fromMap(Map<String, num> typeValuePairs)

Constructs a Dimensions object with a map of base dimension keys to base dimension exponents.

Properties

hashCode → int

Returns a hash code consistent with operator == by constructing a string key based on the dimension component values.

no setter, override

isScalar → bool

Whether or not these are scalar dimensions, including having no angle or solid angle dimensions.

no setter

isScalarSI → bool

Whether or not these are scalar dimensions, in the strict International System of Units (SI) sense, which allows non-zero angle and solid angle dimensions.

no setter

qType → Type?

Optional associated Quantity type

final

runtimeType → Type

A representation of the runtime type of the object.

no setter, inherited

Methods

equalsSI(Dimensions? d2) → bool

Tests the equality of this Dimensions object and d2, only considering the seven base SI quantities (that is, angle and solid angle components are ignored).

getComponentExponent(String component) → num

Gets the exponent value for the specified base dimension component key.

inverse() → Dimensions

Determines the inverse of the dimensions represented by this object, creating a Dimension object. This object is not modified.

noSuchMethod(Invocation invocation) → dynamic

Invoked when a nonexistent method or property is accessed.

inherited

toQuantity([dynamic value = 0.0, Units? units, double uncert = 0.0]) → Quantity

Returns an instance of the Quantity type associated with these dimensions. If no specific Quantity type is found with dimensions that match these dimensions an instance of the MiscQuantity class will be returned. If no value is provided, it defaults to zero. If no units are provided, then MKS units are assumed. If no uncertainty is provided, the value is presumed to be exact.

toString() → String

Returns a String representation of this Dimensions object in the form:

override

Operators

operator *(Dimensions other) → Dimensions

Returns the product of this Dimensions object and other Dimensions.

operator /(Dimensions other) → Dimensions

Divides this Dimension by other Dimensions, creating a Dimensions object.

operator ==(Object d2) → bool

Tests the equality of this Dimensions object and another Dimensions object. Two Dimensions objects are only equal if they have exactly equal values for each component dimension.

override

operator ^(num exp) → Dimensions

Calculates these Dimensions raised to the power specified by exponent

Static Methods

determineQuantityType(Dimensions? dim) → Type

Determines the Quantity type associated with the specified dimensions.

Constants

baseAmountKey → const String

Identifier for Base SI Quantity: Amount of Substance

baseAngleKey → const String

Identifier for Special Derived Dimensionless SI Quantity: Angle

baseCurrentKey → const String

Identifier for Base SI Quantity: Current

baseIntensityKey → const String

Identifier for Base SI Quantity: (Luminous) Intensity

baseLengthKey → const String

Identifier for Base SI Quantity: Length

baseMassKey → const String

Identifier for Base SI Quantity: Mass

baseSolidAngleKey → const String

Identifier for Special Derived Dimensionless SI Quantity: Solid Angle

baseTemperatureKey → const String

Identifier for Base SI Quantity: Temperature

baseTimeKey → const String

Identifier for Base SI Quantity: Time Interval