tec.units.ri.spi.DimensionalModel Maven / Gradle / Ivy
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/*
* Units of Measurement Reference Implementation
* Copyright (c) 2005-2015, Jean-Marie Dautelle, Werner Keil, V2COM.
*
* All rights reserved.
*
* Redistribution and use in source and binary forms, with or without modification,
* are permitted provided that the following conditions are met:
*
* 1. Redistributions of source code must retain the above copyright notice,
* this list of conditions and the following disclaimer.
*
* 2. Redistributions in binary form must reproduce the above copyright notice, this list of conditions
* and the following disclaimer in the documentation and/or other materials provided with the distribution.
*
* 3. Neither the name of JSR-363 nor the names of its contributors may be used to endorse or promote products
* derived from this software without specific prior written permission.
*
* THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
* AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO,
* THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
* ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT HOLDER OR CONTRIBUTORS BE LIABLE
* FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES
* (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES;
* LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED
* AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
* (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE,
* EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
*/
package tec.units.ri.spi;
import java.util.Map;
import javax.measure.Dimension;
import javax.measure.UnitConverter;
import tec.units.ri.AbstractConverter;
import tec.units.ri.quantity.QuantityDimension;
/**
* 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,
* {@link QuantityDimension#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 {@link #getConverter} may
* returns a non-null value for distinct dimensions.
*
* The default model is {@link StandardModel Standard}. Applications may
* use one of the predefined model or create their own.
*
* DimensionalModel relativistic = new DimensionalModel() {
* public Dimension getFundamentalDimension(Dimension 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(Dimension 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);
* }
* };
* try {
* DimensionalModel.setCurrent(relativistic); // Current thread use the relativistic model.
* SI.KILOGRAM.getConverterToAny(SI.JOULE); // Allowed.
* ...
* } finally {
* cleanup();
* }
*
*
* @see Wikipedia: Dimensional Analysis
* @author Jean-Marie Dautelle
* @author Werner Keil
* @version 0.5.6, $Date: 2015-07-25 $
*/
public abstract class DimensionalModel {
/**
* Holds the current model.
*/
private static DimensionalModel currentModel = new StandardModel();
/**
* Returns the current dimensional model
* (by default an instance of {@link StandardModel}).
*
* @return the current physical model.
*/
public static DimensionalModel current() {
return currentModel;
}
/**
* Sets the current dimensional model
*
* @param model the new current model.
* @see #current
*/
protected static void setCurrent(DimensionalModel model) {
currentModel = model;
}
/**
* Default constructor (allows for derivation).
*/
protected DimensionalModel() {
}
/**
* 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.
*
* @param dimension the dimension for which the fundamental dimension is returned.
* @return this or a rational product of fundamental dimension.
*/
public Dimension getFundamentalDimension(Dimension dimension) {
Map dimensions = dimension.getProductDimensions();
if (dimensions == null) return dimension; // Fundamental dimension.
// Dimensional Product.
Dimension fundamentalProduct = QuantityDimension.NONE;
for (Map.Entry e : dimensions.entrySet()) {
fundamentalProduct = fundamentalProduct.multiply(this.getFundamentalDimension(e.getKey())).pow(e.getValue());
}
return fundamentalProduct;
}
/**
* 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.
*
* @param dimension the dimension for which the dimensional transform is returned.
* @return the dimensional transform (identity for fundamental dimensions).
*/
public UnitConverter getDimensionalTransform(Dimension dimension) {
Map dimensions = dimension.getProductDimensions();
if (dimensions == null) return AbstractConverter.IDENTITY; // Fundamental dimension.
// Dimensional Product.
UnitConverter toFundamental = AbstractConverter.IDENTITY;
for (Map.Entry e : dimensions.entrySet()) {
UnitConverter cvtr = this.getDimensionalTransform(e.getKey());
if (!(cvtr.isLinear()))
throw new UnsupportedOperationException("Non-linear dimensional transform");
int pow = e.getValue();
if (pow < 0) { // Negative power.
pow = -pow;
cvtr = cvtr.inverse();
}
for (int j = 0; j < pow; j++) {
toFundamental = toFundamental.concatenate(cvtr);
}
}
return toFundamental;
}
}