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jBasics is a collection of useful utility classes for Java. This includes helper for XML, mathematic functions,
restful web services helper, pattern oriented programming interfaces and more. Currently Java7 and up is
supported. Version 1.0 will required at leaset Java8.
/*
* Copyright (c) 2009-2015
* IT-Consulting Stephan Schloepke (http://www.schloepke.de/)
* klemm software consulting Mirko Klemm (http://www.klemm-scs.com/)
*
* Permission is hereby granted, free of charge, to any person obtaining a copy
* of this software and associated documentation files (the "Software"), to deal
* in the Software without restriction, including without limitation the rights
* to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
* copies of the Software, and to permit persons to whom the Software is
* furnished to do so, subject to the following conditions:
*
* The above copyright notice and this permission notice shall be included in
* all copies or substantial portions of the Software.
*
* THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
* IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
* FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
* AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
* LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
* OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
* THE SOFTWARE.
*/
package org.jbasics.math.impl;
import org.jbasics.math.AlgorithmStrategy;
import org.jbasics.math.IrationalNumber;
import org.jbasics.math.strategies.ArithmeticGeometricMeanAlgorithmStrategy;
import java.math.BigDecimal;
/**
* Calculates the arithmetic geometric mean (agm) of the two given numbers x and y to the {@link IrationalNumber}
* agm(x,y). Can result in a rational number which is exact (for instance the agm(2, 2) is 2). The iteration used to
* find the agm is: - a0 = (x+y)/2
- b0 = √xy
Repeat
* - an+1 = 2-1(an+bn)
- bn+1 =
* √anbn
until an+1 = bn than the result is either
* an or bn (since both are equal)
*
* @author Stephan Schloepke
* @since 1.0
*/
public class ArithmeticGeometricMeanIrationalNumber extends BigDecimalIrationalNumber {
private static final AlgorithmStrategy STRATEGY = new ArithmeticGeometricMeanAlgorithmStrategy();
private ArithmeticGeometricMeanIrationalNumber(BigDecimal x, BigDecimal y) {
super(STRATEGY, x, y);
}
/**
* Returns the irational arithmetic geometric mean of x and y.
*
* @param x The x value (must not be null)
* @param y The y value (must not be null)
*
* @return The agm(x, y)
*
* @since 1.0
*/
public static IrationalNumber valueOf(BigDecimal x, BigDecimal y) {
if (x.signum() == 0 && y.signum() == 0) {
return MathImplConstants.IRATIONAL_ZERO;
} else if (BigDecimal.ONE.compareTo(x) == 0 && BigDecimal.ONE.compareTo(y) == 0) {
return MathImplConstants.IRATIONAL_ONE;
}
return new ArithmeticGeometricMeanIrationalNumber(x, y);
}
}