RdUniform.java

package org.drip.measure.lebesgue;

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

/*!
 * Copyright (C) 2020 Lakshmi Krishnamurthy
 * Copyright (C) 2019 Lakshmi Krishnamurthy
 * Copyright (C) 2018 Lakshmi Krishnamurthy
 * Copyright (C) 2017 Lakshmi Krishnamurthy
 * Copyright (C) 2016 Lakshmi Krishnamurthy
 * Copyright (C) 2015 Lakshmi Krishnamurthy
 * 
 *  This file is part of DROP, an open-source library targeting analytics/risk, transaction cost analytics,
 *      asset liability management analytics, capital, exposure, and margin analytics, valuation adjustment
 *      analytics, and portfolio construction analytics within and across fixed income, credit, commodity,
 *      equity, FX, and structured products. It also includes auxiliary libraries for algorithm support,
 *      numerical analysis, numerical optimization, spline builder, model validation, statistical learning,
 *      and computational support.
 *  
 *      https://lakshmidrip.github.io/DROP/
 *  
 *  DROP is composed of three modules:
 *  
 *  - DROP Product Core - https://lakshmidrip.github.io/DROP-Product-Core/
 *  - DROP Portfolio Core - https://lakshmidrip.github.io/DROP-Portfolio-Core/
 *  - DROP Computational Core - https://lakshmidrip.github.io/DROP-Computational-Core/
 * 
 *  DROP Product Core implements libraries for the following:
 *  - Fixed Income Analytics
 *  - Loan Analytics
 *  - Transaction Cost Analytics
 * 
 *  DROP Portfolio Core implements libraries for the following:
 *  - Asset Allocation Analytics
 *  - Asset Liability Management Analytics
 *  - Capital Estimation Analytics
 *  - Exposure Analytics
 *  - Margin Analytics
 *  - XVA Analytics
 * 
 *  DROP Computational Core implements libraries for the following:
 *  - Algorithm Support
 *  - Computation Support
 *  - Function Analysis
 *  - Model Validation
 *  - Numerical Analysis
 *  - Numerical Optimizer
 *  - Spline Builder
 *  - Statistical Learning
 * 
 *  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
 *  - Repo Layout Taxonomy     => https://github.com/lakshmiDRIP/DROP/blob/master/Taxonomy.md
 *  - 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>RdUniform</i> implements the R<sup>d</sup> Lebesgue Measure Distribution that corresponds to a Uniform
 * R<sup>d</sup> d-Volume Space.
 *
 *  <br><br>
 *  <ul>
 *      <li><b>Module </b> = <a href = "https://github.com/lakshmiDRIP/DROP/tree/master/ComputationalCore.md">Computational Core Module</a></li>
 *      <li><b>Library</b> = <a href = "https://github.com/lakshmiDRIP/DROP/tree/master/NumericalAnalysisLibrary.md">Numerical Analysis Library</a></li>
 *      <li><b>Project</b> = <a href = "https://github.com/lakshmiDRIP/DROP/tree/master/src/main/java/org/drip/measure/README.md">R<sup>d</sup> Continuous/Discrete Probability Measures</a></li>
 *      <li><b>Package</b> = <a href = "https://github.com/lakshmiDRIP/DROP/tree/master/src/main/java/org/drip/measure/lebesgue/README.md">Uniform Piece-wise Lebesgue Measure</a></li>
 *  </ul>
 *
 * @author Lakshmi Krishnamurthy
 */

public class RdUniform extends org.drip.measure.continuous.Rd {
    private org.drip.spaces.tensor.RdGeneralizedVector _gmvs = null;

    /**
     * RdUniform Constructor
     * 
     * @param gmvs The Vector Space Underlying the Measure
     * 
     * @throws java.lang.Exception Thrown if the Inputs are Invalid
     */

    public RdUniform (
        final org.drip.spaces.tensor.RdGeneralizedVector gmvs)
        throws java.lang.Exception
    {
        if (null == (_gmvs = gmvs)) throw new java.lang.Exception ("RdUniform ctr: Invalid Inputs");
    }

    /**
     * Retrieve the Vector Space Underlying the Measure
     * 
     * @return The Vector Space Underlying the Measure
     */

    public org.drip.spaces.tensor.RdGeneralizedVector measureSpace()
    {
        return _gmvs;
    }

    @Override public double cumulative (
        final double[] adblX)
        throws java.lang.Exception
    {
        double[] adblLeftEdge = _gmvs.leftDimensionEdge();

        double dblCumulative = 1.;
        int iDimension = adblLeftEdge.length;

        if (null == adblX || iDimension != adblX.length)
            throw new java.lang.Exception ("RdLebesgue::cumulative => Invalid Inputs");

        double[] adblRightEdge = _gmvs.rightDimensionEdge();

        for (int i = 0; i < iDimension; ++i) {
            if (!org.drip.numerical.common.NumberUtil.IsValid (adblX[i]) || adblX[i] > adblRightEdge[i])
                throw new java.lang.Exception ("RdUniform::cumulative => Invalid Inputs");

            dblCumulative *= (adblX[i] - adblLeftEdge[i]) / (adblRightEdge[i] - adblLeftEdge[i]);
        }

        return dblCumulative;
    }

    @Override public double incremental (
        final double[] adblXLeft,
        final double[] adblXRight)
        throws java.lang.Exception
    {
        if (null == adblXLeft || null == adblXRight)
            throw new java.lang.Exception ("RdUniform::incremental => Invalid Inputs");

        double[] adblLeftEdge = _gmvs.leftDimensionEdge();

        double dblIncremental = 1.;
        int iDimension = adblLeftEdge.length;

        if (iDimension != adblXLeft.length || iDimension != adblXRight.length)
            throw new java.lang.Exception ("RdUniform::incremental => Invalid Inputs");

        double[] adblRightEdge = _gmvs.rightDimensionEdge();

        for (int i = 0; i < iDimension; ++i) {
            if (!org.drip.numerical.common.NumberUtil.IsValid (adblXLeft[i]) || adblXLeft[i] < adblLeftEdge[i] ||
                !org.drip.numerical.common.NumberUtil.IsValid (adblXRight[i]) || adblXRight[i] >
                    adblRightEdge[i])
                throw new java.lang.Exception ("RdUniform::incremental => Invalid Inputs");

            dblIncremental *= (adblXRight[i] - adblXLeft[i]) / (adblRightEdge[i] - adblLeftEdge[i]);
        }

        return dblIncremental;
    }

    @Override public double density (
        final double[] adblX)
        throws java.lang.Exception
    {
        return 1. / _gmvs.hyperVolume();
    }
}