PSeriesSequence.java

package org.drip.sample.lanczos;

import java.util.Map;

import org.drip.numerical.common.FormatUtil;
import org.drip.service.env.EnvManager;
import org.drip.specialfunction.lanczos.PSeriesGenerator;

/*
 * -*- mode: java; tab-width: 4; indent-tabs-mode: nil; c-basic-offset: 4 -*-
 */

/*!
 * Copyright (C) 2019 Lakshmi Krishnamurthy
 * 
 *  This file is part of DROP, an open-source library targeting risk, transaction costs, exposure, margin
 *      calculations, and portfolio construction within and across fixed income, credit, commodity, equity,
 *      FX, and structured products.
 *  
 *      https://lakshmidrip.github.io/DROP/
 *  
 *  DROP is composed of three main modules:
 *  
 *  - DROP Analytics Core - https://lakshmidrip.github.io/DROP-Analytics-Core/
 *  - DROP Portfolio Core - https://lakshmidrip.github.io/DROP-Portfolio-Core/
 *  - DROP Numerical Core - https://lakshmidrip.github.io/DROP-Numerical-Core/
 * 
 *  DROP Analytics Core implements libraries for the following:
 *  - Fixed Income Analytics
 *  - Asset Backed Analytics
 *  - XVA Analytics
 *  - Exposure and Margin Analytics
 * 
 *  DROP Portfolio Core implements libraries for the following:
 *  - Asset Allocation Analytics
 *  - Transaction Cost Analytics
 * 
 *  DROP Numerical Core implements libraries for the following:
 *  - Statistical Learning Library
 *  - Numerical Optimizer Library
 *  - Machine Learning Library
 *  - Spline Builder Library
 * 
 *  Documentation for DROP is Spread Over:
 * 
 *  - Main                     => https://lakshmidrip.github.io/DROP/
 *  - Wiki                     => https://github.com/lakshmiDRIP/DROP/wiki
 *  - GitHub                   => https://github.com/lakshmiDRIP/DROP
 *  - Javadoc                  => https://lakshmidrip.github.io/DROP/Javadoc/index.html
 *  - Technical Specifications => https://github.com/lakshmiDRIP/DROP/tree/master/Docs/Internal
 *  - Release Versions         => https://lakshmidrip.github.io/DROP/version.html
 *  - Community Credits        => https://lakshmidrip.github.io/DROP/credits.html
 *  - Issues Catalog           => https://github.com/lakshmiDRIP/DROP/issues
 *  - JUnit                    => https://lakshmidrip.github.io/DROP/junit/index.html
 *  - Jacoco                   => https://lakshmidrip.github.io/DROP/jacoco/index.html
 * 
 *  Licensed under the Apache License, Version 2.0 (the "License");
 *      you may not use this file except in compliance with the License.
 *   
 *  You may obtain a copy of the License at
 *      http://www.apache.org/licenses/LICENSE-2.0
 *  
 *  Unless required by applicable law or agreed to in writing, software
 *      distributed under the License is distributed on an "AS IS" BASIS,
 *      WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 *  
 *  See the License for the specific language governing permissions and
 *      limitations under the License.
 */

/**
 * <i>PSeriesSequence</i> illustrates the Generation of the Lanczos P Series for different Values of the g
 * Control. The References are:
 * 
 * <br><br>
 *  <ul>
 *      <li>
 *          Godfrey, P. (2001): Lanczos Implementation of the Gamma Function
 *              http://www.numericana.com/answer/info/godfrey.htm
 *      </li>
 *      <li>
 *          Press, W. H., S. A. Teukolsky, W. T. Vetterling, and B. P. Flannery (2007): <i>Numerical Recipes:
 *              The Art of Scientific Computing 3rd Edition</i> <b>Cambridge University Press</b> New York
 *      </li>
 *      <li>
 *          Pugh, G. R. (2004): <i>An Analysis of the Lanczos Gamma Approximation</i> Ph. D. <b>University of
 *              British Columbia</b>
 *      </li>
 *      <li>
 *          Toth V. T. (2016): Programmable Calculators – The Gamma Function
 *              http://www.rskey.org/CMS/index.php/the-library/11
 *      </li>
 *      <li>
 *          Wikipedia (2019): Lanczos Approximation https://en.wikipedia.org/wiki/Lanczos_approximation
 *      </li>
 *  </ul>
 *
 *  <br><br>
 *  <ul>
 *      <li><b>Module </b> = <a href = "https://github.com/lakshmiDRIP/DROP/tree/master/NumericalCore.md">Numerical Core Module</a></li>
 *      <li><b>Library</b> = <a href = "https://github.com/lakshmiDRIP/DROP/tree/master/NumericalOptimizerLibrary.md">Numerical Optimizer</a></li>
 *      <li><b>Project</b> = <a href = "https://github.com/lakshmiDRIP/DROP/tree/master/src/main/java/org/drip/sample/README.md">Sample</a></li>
 *      <li><b>Package</b> = <a href = "https://github.com/lakshmiDRIP/DROP/tree/master/src/main/java/org/drip/sample/lanczos/README.md">Lanczos Gamma Calculation Scheme Illustration</a></li>
 *  </ul>
 *
 * @author Lakshmi Krishnamurthy
 */

public class PSeriesSequence
{

    private static final void DisplaySeries (
        final int g,
        final Map<Integer, Double> orderedSeries)
        throws Exception
    {
        String series = "\t|" + FormatUtil.FormatDouble (g, 2, 0, 1.) + " => ";

        for (Map.Entry<Integer, Double> seriesEntry : orderedSeries.entrySet())
        {
            series = series + " " + FormatUtil.FormatDouble (seriesEntry.getValue(), 8, 0, 1.) + " |";
        }

        System.out.println (series + "|");
    }

    public static final void main (
        final String[] argumentArray)
        throws Exception
    {
        EnvManager.InitEnv ("");

        int termCount = 10;
        int[] gArray = 
        {
            3,
            4,
            5,
            6,
            7,
            8,
            9,
            10
        };

        System.out.println
            ("\t|------------------------------------------------------------------------------------------------------------------------------------------||");

        System.out.println
            ("\t|                                                            P-SERIES SEQUENCE                                                             ||");

        System.out.println
            ("\t|------------------------------------------------------------------------------------------------------------------------------------------||");

        System.out.println
            ("\t|        L -> R:                                                                                                                           ||");

        System.out.println
            ("\t|                - g                                                                                                                       ||");

        System.out.println
            ("\t|                - P Series Coefficients                                                                                                   ||");

        System.out.println
            ("\t|------------------------------------------------------------------------------------------------------------------------------------------||");

        for (int g : gArray)
        {
            DisplaySeries (
                g,
                PSeriesGenerator.Standard (
                    g,
                    termCount
                ).generate (0.)
            );
        }

        System.out.println
            ("\t|------------------------------------------------------------------------------------------------------------------------------------------||");

        EnvManager.TerminateEnv();
    }
}