HyperbolicTension.java

package org.drip.function.r1tor1;

/*
 * -*- 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
 * Copyright (C) 2014 Lakshmi Krishnamurthy
 * Copyright (C) 2013 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>HyperbolicTension</i> provides the evaluation of the Hyperbolic Tension Function and its derivatives
 * for a specified variate.
 *
 *	<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/function/README.md">R<sup>d</sup> To R<sup>d</sup> Function Analysis</a></li>
 *		<li><b>Package</b> = <a href = "https://github.com/lakshmiDRIP/DROP/tree/master/src/main/java/org/drip/function/r1tor1/README.md">Built-in R<sup>1</sup> To R<sup>1</sup> Functions</a></li>
 *  </ul>
 *
 * @author Lakshmi Krishnamurthy
 */

public class HyperbolicTension extends org.drip.function.definition.R1ToR1 {

	/**
	 * Hyperbolic Tension Function Type - sinh
	 */

	public static final int SINH = 1;

	/**
	 * Hyperbolic Tension Function Type - cosh
	 */

	public static final int COSH = 2;

	private int _iType = -1;
	private double _dblTension = java.lang.Double.NaN;

	/**
	 * HyperbolicTension constructor
	 * 
	 * @param iType Type of the HyperbolicTension Function - SINH/COSH/TANH
	 * @param dblTension Tension of the HyperbolicTension Function
	 * 
	 * @throws java.lang.Exception Thrown if the input is invalid
	 */

	public HyperbolicTension (
		final int iType,
		final double dblTension)
		throws java.lang.Exception
	{
		super (null);

		if ((SINH != (_iType = iType) && COSH != _iType) || !org.drip.numerical.common.NumberUtil.IsValid
			(_dblTension = dblTension))
			throw new java.lang.Exception ("HyperbolicTension ctr: Invalid Inputs");
	}

	@Override public double evaluate (
		final double dblVariate)
		throws java.lang.Exception
	{
		if (!org.drip.numerical.common.NumberUtil.IsValid (dblVariate))
			throw new java.lang.Exception ("HyperbolicTension::evaluate => Invalid Inputs");

		return SINH == _iType ? java.lang.Math.sinh (_dblTension * dblVariate) : java.lang.Math.cosh
			(_dblTension * dblVariate);
	}

	@Override public double derivative (
		final double dblVariate,
		final int iOrder)
		throws java.lang.Exception
	{
		if (!org.drip.numerical.common.NumberUtil.IsValid (dblVariate) || 0 > iOrder)
			throw new java.lang.Exception ("HyperbolicTension::derivative => Invalid Inputs");

		double dblDerivFactor = 1.;

		for (int i = 0; i < iOrder; ++i)
			dblDerivFactor *= _dblTension;

		return (SINH == _iType) ? dblDerivFactor * (1 == iOrder % 2 ? java.lang.Math.cosh (_dblTension *
			dblVariate) : java.lang.Math.sinh (_dblTension * dblVariate)) : dblDerivFactor * (1 == iOrder % 2
				? java.lang.Math.sinh (_dblTension * dblVariate) : java.lang.Math.cosh (_dblTension *
					dblVariate));
	}

	@Override public double integrate (
		final double dblBegin,
		final double dblEnd)
		throws java.lang.Exception
	{
		if (!org.drip.numerical.common.NumberUtil.IsValid (dblBegin) || !org.drip.numerical.common.NumberUtil.IsValid
			(dblEnd))
			throw new java.lang.Exception ("HyperbolicTension::integrate => Invalid Inputs");

		return SINH == _iType ? (java.lang.Math.cosh (_dblTension * dblEnd) - java.lang.Math.cosh
			(_dblTension * dblBegin)) / _dblTension : (java.lang.Math.sinh (_dblTension * dblEnd) -
				java.lang.Math.sinh (_dblTension * dblBegin)) / _dblTension;
	}

	/**
	 * Retrieve the hyperbolic function type
	 * 
	 * @return Hyperbolic function type
	 */

	public int getType()
	{
		return _iType;
	}

	/**
	 * Retrieve the Tension Parameter
	 * 
	 * @return Tension Parameter
	 */

	public double getTension()
	{
		return _dblTension;
	}

	public static final void main (
		final java.lang.String[] astrArgs)
		throws java.lang.Exception
	{
		HyperbolicTension e = new HyperbolicTension (SINH, 2.);

		System.out.println ("E[0.0] = " + e.evaluate (0.0));

		System.out.println ("E[0.5] = " + e.evaluate (0.5));

		System.out.println ("E[1.0] = " + e.evaluate (1.0));

		System.out.println ("EDeriv[0.0] = " + e.derivative (0.0, 2));

		System.out.println ("EDeriv[0.5] = " + e.derivative (0.5, 2));

		System.out.println ("EDeriv[1.0] = " + e.derivative (1.0, 2));
	}
}