AlgorithmStrategy.java

/*
 * 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;

import java.math.BigDecimal;
import java.math.MathContext;

/**
 * The algorithm strategy is an implementation of an algorithm so it can be replaced for certain situations. <p> Think
 * about the E function. There is an almost pure integer algorithm not requiring a division until last. This algorithm
 * is quite a bit faster than the usual tayler series processed on decimals. However since the algorithm is performed
 * using rationals and also requires at least two faculties it has a bigger memory impact calculating. </p> <p> So there
 * are situations you need the most possible speed regardless of the memory used and there are situations where you
 * require a very memory efficient algorithm since you know that you do not require a huge precision. In order to
 * replace certain algorithms depending on the situation they need to plugable. That is what this {@link
 * AlgorithmStrategy} is supposed to do. </p>
 *
 * @param <T>
 *
 * @author Stephan Schloepke
 * @since 1.0
 */
public interface AlgorithmStrategy<T> {

	/**
	 * Calculate the given input value(s) optionally giving a guess of the possible result (f(x<sub>0</sub>, …
	 * ,x<sub>n</sub>) = result) <p> </p>
	 *
	 * @param mc    The calculation math context
	 * @param guess An initial guess which can be used if possible by the algorithm. In case you have a less precise
	 *              number you could input this to the algorithm and in some cases (like Newton Iteration) it is
	 *              possible to start the algorithm at the guess yielding a faster result.
	 * @param xn    The input series x<sub>0</sub>, … ,x<sub>n</sub>
	 *
	 * @return The approximated or correct number resulting from the calculation. It is expected that if the precision
	 * of the result is less than the precision of the math context that it is indeed an exact result and not
	 * approximated.
	 *
	 * @since 1.0
	 */
	T calculate(MathContext mc, BigDecimal guess, BigDecimal... xn);
}