//                                               -*- C++ -*-
/**
 *  @file  ChiSquare.hxx
 *  @brief The ChiSquare distribution
 *
 *  Copyright (C) 2005-2013 EDF-EADS-Phimeca
 *
 *  This library is free software: you can redistribute it and/or modify
 *  it under the terms of the GNU Lesser General Public License as published by
 *  the Free Software Foundation, either version 3 of the License, or
 *  (at your option) any later version.
 *
 *  This library is distributed in the hope that it will be useful,
 *  but WITHOUT ANY WARRANTY; without even the implied warranty of
 *  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 *  GNU Lesser General Public License for more details.
 *
 *  You should have received a copy of the GNU Lesser General Public
 *  along with this library.  If not, see <http://www.gnu.org/licenses/>.
 *
 *  @author lebrun
 *  @date   2008-11-23 16:03:50 +0100 (dim, 23 nov 2008)
 */
#ifndef OPENTURNS_CHISQUARE_HXX
#define OPENTURNS_CHISQUARE_HXX

#include "ContinuousDistribution.hxx"

BEGIN_NAMESPACE_OPENTURNS

/**
 * @class ChiSquare
 *
 * The ChiSquare distribution.
 */
class ChiSquare
  : public ContinuousDistribution
{
  CLASSNAME;
public:

  /** Default constructor */
  ChiSquare();

  /** Parameters constructor */
  ChiSquare(const NumericalScalar nu_);


  /** Comparison operator */
  Bool operator ==(const ChiSquare & other) const;

  /** String converter */
  String __repr__() const;
  String __str__(const String & offset = "") const;



  /* Interface inherited from Distribution */

  /** Virtual constructor */
  virtual ChiSquare * clone() const;

  /** Get one realization of the distribution */
  NumericalPoint getRealization() const;

  /** Get the DDF of the distribution */
  using ContinuousDistribution::computeDDF;
  NumericalPoint computeDDF(const NumericalPoint & point) const;

  /** Get the PDF of the distribution */
  using ContinuousDistribution::computePDF;
  NumericalScalar computePDF(const NumericalPoint & point) const;

  /** Get the logarithm of the PDF of the distribution */
  using ContinuousDistribution::computeLogPDF;
  NumericalScalar computeLogPDF(const NumericalPoint & point) const;

  /** Get the CDF of the distribution */
  using ContinuousDistribution::computeCDF;
  NumericalScalar computeCDF(const NumericalPoint & point) const;
  using ContinuousDistribution::computeComplementaryCDF;
  NumericalScalar computeComplementaryCDF(const NumericalPoint & point) const;

  /** Get the characteristic function of the distribution, i.e. phi(u) = E(exp(I*u*X)) */
  NumericalComplex computeCharacteristicFunction(const NumericalScalar x) const;
  NumericalComplex computeLogCharacteristicFunction(const NumericalScalar x) const;

  /** Get the PDFGradient of the distribution */
  NumericalPoint computePDFGradient(const NumericalPoint & point) const;

  /** Get the CDFGradient of the distribution */
  NumericalPoint computeCDFGradient(const NumericalPoint & point) const;

  /** Get the standard deviation of the distribution */
  NumericalPoint getStandardDeviation() const;

  /** Get the skewness of the distribution */
  NumericalPoint getSkewness() const;

  /** Get the kurtosis of the distribution */
  NumericalPoint getKurtosis() const;

  /** Get the raw moments of the standardized distribution */
  NumericalPoint getStandardMoment(const UnsignedLong n) const;

  /** Parameters value and description accessor */
  NumericalPointWithDescriptionCollection getParametersCollection() const;
  using ContinuousDistribution::setParametersCollection;
  void setParametersCollection(const NumericalPointCollection & parametersCollection);

  /* Interface specific to ChiSquare */

  /** Nu accessor */
  void setNu(const NumericalScalar nu);
  NumericalScalar getNu() const;

  /** Method save() stores the object through the StorageManager */
  void save(Advocate & adv) const;

  /** Method load() reloads the object from the StorageManager */
  void load(Advocate & adv);


protected:


private:

  /** Compute the mean of the distribution */
  void computeMean() const;

  /** Compute the covariance of the distribution */
  void computeCovariance() const;

  /** Get the quantile of the distribution */
  NumericalScalar computeScalarQuantile(const NumericalScalar prob,
                                        const Bool tail = false) const;

  /** Compute the numerical range of the distribution given the parameters values */
  void computeRange();

  /** Update the derivative attributes */
  void update();

  /** The main parameter set of the distribution */
  NumericalScalar nu_;
  NumericalScalar normalizationFactor_;

}; /* class ChiSquare */


END_NAMESPACE_OPENTURNS

#endif /* OPENTURNS_CHISQUARE_HXX */
