/home/marsyas/marsyas/src/marsyas/Skewness.cpp

/*
** Copyright (C) 1998-2006 George Tzanetakis <gtzan@cs.uvic.ca>
**  
** This program is free software; you can redistribute it and/or modify
** it under the terms of the GNU General Public License as published by
** the Free Software Foundation; either version 2 of the License, or
** (at your option) any later version.
** 
** This program 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 General Public License for more details.
** 
** You should have received a copy of the GNU General Public License
** along with this program; if not, write to the Free Software 
** Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA.
*/

#include "Skewness.h"

using namespace std;
using namespace Marsyas;

Skewness::Skewness(mrs_string name):MarSystem("Skewness",name)
{
  //type_ = "Skewness";
  //name_ = name;
}


Skewness::~Skewness()
{
}


MarSystem* 
Skewness::clone() const 
{
  return new Skewness(*this);
}


void
Skewness::myUpdate(MarControlPtr sender)
{
    (void) sender;
  MRSDIAG("Skewness.cpp - Skewness:myUpdate");
  
  setctrl("mrs_natural/onSamples", getctrl("mrs_natural/inSamples"));
  setctrl("mrs_natural/onObservations", (mrs_natural)1);
  setctrl("mrs_real/osrate", getctrl("mrs_real/israte"));
  setctrl("mrs_string/onObsNames", "Skewness,");
  
    //defaultUpdate();[!]
    inObservations_ = getctrl("mrs_natural/inObservations")->to<mrs_natural>();

  obsrow_.create(inObservations_);
}


void 
Skewness::myProcess(realvec& in, realvec& out)
{
  mrs_natural t,o;

  for (t = 0; t < inSamples_; t++)
    {
      
      for (o=0; o < inObservations_; o++)
        {
          obsrow_(o) = in(o,t);
        }
      z_ = 0.0;
      for (o=0; o < inObservations_; o++)
        {
          b_ =  obsrow_(o) - obsrow_.mean() ;
          
          // take x - mean to the third power into the sum
          z_ += (b_ * b_ * b_); 
        }
      if (z_ > 1.0e-45)
        z_ /= inObservations_;
      else
        z_ = 0.0;

      
      // standard deviation to the fourth power
      q_ = pow(obsrow_.var(), (mrs_real)1.5);

      if ((q_ < 1.0e-45)||(z_== 1.0e-45))
        out(0,t) = 0.5;
      else 
        out(0,t) = (z_ / q_)  / inObservations_;
    }
    
}

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