001/*
002 * Units of Measurement Reference Implementation
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.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 1.0, October 6, 2016
044 * @since 1.0
045 */
046public final class PiMultiplierConverter extends AbstractConverter implements ValueSupplier<String> {
047
048  /**
049   * Creates a Pi multiplier converter.
050   */
051  public PiMultiplierConverter() {
052  }
053
054  @Override
055  public double convert(double value) {
056    return value * PI;
057  }
058
059  // @Override
060  // public BigDecimal convert(BigDecimal value, MathContext ctx)
061  // throws ArithmeticException {
062  // int nbrDigits = ctx.getPrecision();
063  // if (nbrDigits == 0)
064  // throw new ArithmeticException(
065  // "Pi multiplication with unlimited precision");
066  // BigDecimal pi = Pi.pi(nbrDigits);
067  // return value.multiply(pi, ctx).scaleByPowerOfTen(1 - nbrDigits);
068  // }
069  @Override
070  public AbstractConverter inverse() {
071    return new PiDivisorConverter();
072  }
073
074  @Override
075  public final String toString() {
076    return "(?)";
077  }
078
079  @Override
080  public boolean equals(Object obj) {
081    return (obj instanceof PiMultiplierConverter);
082  }
083
084  @Override
085  public int hashCode() {
086    return 0;
087  }
088
089  public boolean isLinear() {
090    return true;
091  }
092
093  /**
094   * Pi calculation with Machin's formula.
095   * 
096   * @see <a href="http://en.literateprograms.org/Pi_with_Machin's_formula_(Java)" >Pi with Machin's formula</a>
097   * 
098   */
099  // static final class Pi {
100  //
101  // private Pi() {
102  // }
103  //
104  // public static Double pi(int numDigits) {
105  // int calcDigits = numDigits + 10;
106  // return 4 * ((4 * (arccot(5, calcDigits))) - arccot(239, calcDigits)); /*
107  // * )
108  // * .
109  // * setScale
110  // * (
111  // * numDigits
112  // * ,
113  // * RoundingMode
114  // * .
115  // * DOWN
116  // * )
117  // * ;
118  // */
119  // }
120  //
121  // private static double arccot(double x, int numDigits) {
122  // double unity = 1; /*
123  // * BigDecimal.ONE.setScale(numDigits,
124  // * RoundingMode.DOWN);
125  // */
126  // double sum = unity / x;
127  // double xpower = sum;
128  // Double term = null;
129  // boolean add = false;
130  // for (double n = 3; term == null || !term.equals(Double.valueOf(0)); n += 2) {
131  // xpower = xpower / ((long) x ^ 2);
132  // term = xpower / n;
133  // sum = add ? sum + term : sum - term;
134  // add = !add;
135  // }
136  // return sum;
137  // }
138  // }
139  // private static final BigDecimal TWO = new BigDecimal("2");
140  // private static final BigDecimal FOUR = new BigDecimal("4");
141  // private static final BigDecimal FIVE = new BigDecimal("5");
142  // private static final BigDecimal TWO_THIRTY_NINE = new BigDecimal("239");
143  public String getValue() {
144    return toString();
145  }
146}