tech.uom.impl.enums

Class DimensionalModel

java.lang.Object

tech.uom.impl.enums.DimensionalModel

Direct Known Subclasses:

StandardModel

public abstract class DimensionalModel
extends Object

This class represents the physical model used for dimensional analysis.

In principle, dimensions of physical quantities could be defined as "fundamental" (such as momentum or energy or electric current) making such quantities uncommensurate (not comparable). Modern physics has cast doubt on the very existence of incompatible fundamental dimensions of physical quantities. For example, most physicists do not recognize temperature, Θ, as a fundamental dimension since it essentially expresses the energy per particle per degree of freedom, which can be expressed in terms of energy (or mass, length, and time). To support, such model the method #getConverter may returns a non-null value for distinct dimensions.

The default model is Standard. Applications may use one of the predefined model or create their own. [code] DimensionalModel relativistic = new DimensionalModel() { public Dimension getFundamentalDimension(QuantityDimension dimension) { if (dimension.equals(QuantityDimension.LENGTH)) return QuantityDimension.TIME; // Consider length derived from time. return super.getDimension(dimension); // Returns product of fundamental dimension. } public UnitConverter getDimensionalTransform(QuantityDimension dimension) { if (dimension.equals(QuantityDimension.LENGTH)) return new RationalConverter(1, 299792458); // Converter (1/C) from LENGTH SI unit (m) to TIME SI unit (s). return super.getDimensionalTransform(dimension); } }; LocalContext.enter(); try { DimensionalModel.setCurrent(relativistic); // Current thread use the relativistic model. SI.KILOGRAM.getConverterToAny(SI.JOULE); // Allowed. ... } finally { LocalContext.exit(); } [/code]

Version:

0.2, $Date$

Author:

Werner Keil

See Also:

Wikipedia: Dimensional Analysis

Constructor Summary

Constructors

Modifier	Constructor and Description
protected	DimensionalModel() Default constructor (allows for derivation).

Method Summary

Modifier and Type	Method and Description
static DimensionalModel	current() Returns the physics model used by the current thread (by default an instance of StandardModel).
javax.measure.UnitConverter	getDimensionalTransform(javax.measure.Dimension dimension) Returns the dimensional transform of the specified dimension.
javax.measure.Dimension	getFundamentalDimension(javax.measure.Dimension dimension) Returns the fundamental dimension for the one specified.

Methods inherited from class java.lang.Object

clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

Constructor Detail

DimensionalModel

protected DimensionalModel()

Default constructor (allows for derivation).

Method Detail

current

public static DimensionalModel current()

Returns the physics model used by the current thread (by default an instance of StandardModel).

Returns:

the getCurrent physical model.

See Also:

LocalContext

getFundamentalDimension

public javax.measure.Dimension getFundamentalDimension(javax.measure.Dimension dimension)

Returns the fundamental dimension for the one specified. If the specified dimension is a dimensional product, the dimensional product of its fundamental dimensions is returned. Physical quantities are considered commensurate only if their fundamental dimensions are equals using the current physics model.

Parameters:

dimension - the dimension for which the fundamental dimension is returned.

Returns:

this or a rational product of fundamental dimension.

getDimensionalTransform

public javax.measure.UnitConverter getDimensionalTransform(javax.measure.Dimension dimension)

Returns the dimensional transform of the specified dimension. If the specified dimension is a fundamental dimension or a product of fundamental dimensions the identity converter is returned; otherwise the converter from the system unit (SI) of the specified dimension to the system unit (SI) of its fundamental dimension is returned.

Parameters:

dimension - the dimension for which the dimensional transform is returned.

Returns:

the dimensional transform (identity for fundamental dimensions).