001/* 002 * Units of Measurement Implementation for Java SE 003 * Copyright (c) 2005-2017, Jean-Marie Dautelle, Werner Keil, V2COM. 004 * 005 * All rights reserved. 006 * 007 * Redistribution and use in source and binary forms, with or without modification, 008 * are permitted provided that the following conditions are met: 009 * 010 * 1. Redistributions of source code must retain the above copyright notice, 011 * this list of conditions and the following disclaimer. 012 * 013 * 2. Redistributions in binary form must reproduce the above copyright notice, this list of conditions 014 * and the following disclaimer in the documentation and/or other materials provided with the distribution. 015 * 016 * 3. Neither the name of JSR-363 nor the names of its contributors may be used to endorse or promote products 017 * derived from this software without specific prior written permission. 018 * 019 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS" 020 * AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, 021 * THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE 022 * ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT HOLDER OR CONTRIBUTORS BE LIABLE 023 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES 024 * (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; 025 * LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED 026 * AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT 027 * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, 028 * EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE. 029 */ 030package tec.uom.se.spi; 031 032import tec.uom.se.AbstractConverter; 033import tec.uom.se.quantity.QuantityDimension; 034import javax.measure.Dimension; 035import java.util.Map; 036 037/** 038 * <p> 039 * This class represents the physical model used for dimensional analysis. 040 * </p> 041 * 042 * <p> 043 * In principle, dimensions of physical quantities could be defined as "fundamental" (such as momentum or energy or electric current) making such 044 * quantities uncommensurate (not comparable). Modern physics has cast doubt on the very existence of incompatible fundamental dimensions of physical 045 * quantities. For example, most physicists do not recognize temperature, {@link QuantityDimension#TEMPERATURE Θ}, as a fundamental dimension since it 046 * essentially expresses the energy per particle per degree of freedom, which can be expressed in terms of energy (or mass, length, and time). To 047 * support, such model the method {@link #getConverter} may returns a non-null value for distinct dimensions. 048 * </p> 049 * 050 * <p> 051 * The default model is {@link StandardModel Standard}. Applications may use one of the predefined model or create their own. <code> 052 * DimensionalModel relativistic = new DimensionalModel() { 053 * public Dimension getFundamentalDimension(Dimension dimension) { 054 * if (dimension.equals(QuantityDimension.LENGTH)) return QuantityDimension.TIME; // Consider length derived from time. 055 * return super.getDimension(dimension); // Returns product of fundamental dimension. 056 * } 057 * public UnitConverter getDimensionalTransform(Dimension dimension) { 058 * if (dimension.equals(QuantityDimension.LENGTH)) return new RationalConverter(1, 299792458); // Converter (1/C) from LENGTH SI unit (m) to TIME SI unit (s). 059 * return super.getDimensionalTransform(dimension); 060 * } 061 * }; 062 * try { 063 * DimensionalModel.setCurrent(relativistic); // Current thread use the relativistic model. 064 * Units.KILOGRAM.getConverterToAny(Units.JOULE); // Allowed. 065 * ... 066 * } finally { 067 * cleanup(); 068 * } 069 * </code> 070 * </p> 071 * 072 * @see <a href="http://en.wikipedia.org/wiki/Dimensional_analysis">Wikipedia: Dimensional Analysis</a> 073 * @author <a href="mailto:jean-marie@dautelle.com">Jean-Marie Dautelle</a> 074 * @author <a href="mailto:units@catmedia.us">Werner Keil</a> 075 * @version 0.5.5, $Date: 2015-07-25 $ 076 */ 077public abstract class DimensionalModel { 078 079 /** 080 * Holds the current model. 081 */ 082 private static DimensionalModel currentModel = new StandardModel(); 083 084 /** 085 * Returns the current model (by default an instance of {@link StandardModel}). 086 * 087 * @return the current dimensional model. 088 */ 089 public static DimensionalModel current() { 090 return currentModel; 091 } 092 093 /** 094 * Sets the current dimensional model 095 * 096 * @param model 097 * the new current model. 098 * @see #current 099 */ 100 protected static void setCurrent(DimensionalModel model) { 101 currentModel = model; 102 } 103 104 /** 105 * DefaultQuantityFactory constructor (allows for derivation). 106 */ 107 protected DimensionalModel() { 108 } 109 110 /** 111 * Returns the fundamental dimension for the one specified. If the specified dimension is a dimensional product, the dimensional product of its 112 * fundamental dimensions is returned. Physical quantities are considered commensurate only if their fundamental dimensions are equals using the 113 * current physics model. 114 * 115 * @param dimension 116 * the dimension for which the fundamental dimension is returned. 117 * @return <code>this</code> or a rational product of fundamental dimension. 118 */ 119 public Dimension getFundamentalDimension(Dimension dimension) { 120 Map<? extends Dimension, Integer> dimensions = dimension.getBaseDimensions(); 121 if (dimensions == null) 122 return dimension; // Fundamental dimension. 123 // Dimensional Product. 124 Dimension fundamentalProduct = QuantityDimension.NONE; 125 for (Map.Entry<? extends Dimension, Integer> e : dimensions.entrySet()) { 126 fundamentalProduct = fundamentalProduct.multiply(this.getFundamentalDimension(e.getKey())).pow(e.getValue()); 127 } 128 return fundamentalProduct; 129 } 130 131 /** 132 * Returns the dimensional transform of the specified dimension. If the specified dimension is a fundamental dimension or a product of fundamental 133 * dimensions the identity converter is returned; otherwise the converter from the system unit (SI) of the specified dimension to the system unit 134 * (SI) of its fundamental dimension is returned. 135 * 136 * @param dimension 137 * the dimension for which the dimensional transform is returned. 138 * @return the dimensional transform (identity for fundamental dimensions). 139 */ 140 public AbstractConverter getDimensionalTransform(Dimension dimension) { 141 Map<? extends Dimension, Integer> dimensions = dimension.getBaseDimensions(); 142 if (dimensions == null) 143 return AbstractConverter.IDENTITY; // Fundamental dimension. 144 // Dimensional Product. 145 AbstractConverter toFundamental = AbstractConverter.IDENTITY; 146 for (Map.Entry<? extends Dimension, Integer> e : dimensions.entrySet()) { 147 AbstractConverter cvtr = this.getDimensionalTransform(e.getKey()); 148 if (!(cvtr.isLinear())) 149 throw new UnsupportedOperationException("Non-linear dimensional transform"); 150 int pow = e.getValue(); 151 if (pow < 0) { // Negative power. 152 pow = -pow; 153 cvtr = cvtr.inverse(); 154 } 155 for (int j = 0; j < pow; j++) { 156 toFundamental = toFundamental.concatenate(cvtr); 157 } 158 } 159 return toFundamental; 160 } 161}