PearsonVI.h

//-*-C++-*-
/***************************************************************************
 *
 *   Copyright (C) 2008 - 2023 by Andrew Jameson and Willem van Straten
 *   Licensed under the Academic Free License version 2.1
 *
 ***************************************************************************/
 
#ifndef __dsp_Signal_Statistics_PearsonVI_h
#define __dsp_Signal_Statistics_PearsonVI_h
 
#include "dsp/ProbabilityDensity.h"
 
namespace dsp {
 
  class PearsonVI : public ProbabilityDensity {
 
  public:
 
    class Parameters
    {
      public:
        double mu1;
        double mu2;
        double mu3;
        double mu4;
 
      double get_alpha();
      double get_beta();
      double get_sqrt(); // returns the common term (inside the sqrt) in alpha and beta
    };
    
    PearsonVI (const Parameters&);
 
    double evaluate (double x);
 
    double get_alpha () { return alpha; }
    double get_beta () { return beta; }
    double get_delta () { return delta; }
 
  private:
 
    void prepare();
 
    Parameters stats;
 
    double alpha;
    double beta;
    double delta;
 
    // natural logarithm of Pearson type VI normalisation factor
    double logk;
  };
}
 
#endif