001/*
002 * Units of Measurement Reference Implementation
003 * Copyright (c) 2005-2016, 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.units.ri.function;
031
032import tec.units.ri.AbstractConverter;
033import tec.uom.lib.common.function.ValueSupplier;
034
035/**
036 * <p>
037 * This class represents a converter multiplying numeric values by ? (Pi).
038 * </p>
039 * 
040 * @see <a href="http://en.wikipedia.org/wiki/Pi"> Wikipedia: Pi</a>
041 * @author <a href="mailto:jean-marie@dautelle.com">Jean-Marie Dautelle</a>
042 * @author <a href="mailto:units@catmedia.us">Werner Keil</a>
043 * @version 0.4, December 28, 2015
044 */
045public final class PiMultiplierConverter extends AbstractConverter implements ValueSupplier<String> {
046
047  /**
048   * Creates a Pi multiplier converter.
049   */
050  public PiMultiplierConverter() {
051  }
052
053  @Override
054  public double convert(double value) {
055    return value * PI;
056  }
057
058  // @Override
059  // public BigDecimal convert(BigDecimal value, MathContext ctx)
060  // throws ArithmeticException {
061  // int nbrDigits = ctx.getPrecision();
062  // if (nbrDigits == 0)
063  // throw new ArithmeticException(
064  // "Pi multiplication with unlimited precision");
065  // BigDecimal pi = Pi.pi(nbrDigits);
066  // return value.multiply(pi, ctx).scaleByPowerOfTen(1 - nbrDigits);
067  // }
068  @Override
069  public AbstractConverter inverse() {
070    return new PiDivisorConverter();
071  }
072
073  @Override
074  public final String toString() {
075    return "(?)";
076  }
077
078  @Override
079  public boolean equals(Object obj) {
080    return (obj instanceof PiMultiplierConverter);
081  }
082
083  @Override
084  public int hashCode() {
085    return 0;
086  }
087
088  public boolean isLinear() {
089    return true;
090  }
091
092  /**
093   * Pi calculation with Machin's formula.
094   * 
095   * @see <a href="http://en.literateprograms.org/Pi_with_Machin's_formula_(Java)" >Pi with Machin's formula</a>
096   * 
097   */
098  // static final class Pi {
099  //
100  // private Pi() {
101  // }
102  //
103  // public static Double pi(int numDigits) {
104  // int calcDigits = numDigits + 10;
105  // return 4 * ((4 * (arccot(5, calcDigits))) - arccot(239, calcDigits)); /*
106  // * )
107  // * .
108  // * setScale
109  // * (
110  // * numDigits
111  // * ,
112  // * RoundingMode
113  // * .
114  // * DOWN
115  // * )
116  // * ;
117  // */
118  // }
119  //
120  // private static double arccot(double x, int numDigits) {
121  // double unity = 1; /*
122  // * BigDecimal.ONE.setScale(numDigits,
123  // * RoundingMode.DOWN);
124  // */
125  // double sum = unity / x;
126  // double xpower = sum;
127  // Double term = null;
128  // boolean add = false;
129  // for (double n = 3; term == null || !term.equals(Double.valueOf(0)); n += 2) {
130  // xpower = xpower / ((long) x ^ 2);
131  // term = xpower / n;
132  // sum = add ? sum + term : sum - term;
133  // add = !add;
134  // }
135  // return sum;
136  // }
137  // }
138  // private static final BigDecimal TWO = new BigDecimal("2");
139  // private static final BigDecimal FOUR = new BigDecimal("4");
140  // private static final BigDecimal FIVE = new BigDecimal("5");
141  // private static final BigDecimal TWO_THIRTY_NINE = new BigDecimal("239");
142  public String getValue() {
143    return toString();
144  }
145}