Math.cpp

Go to the documentation of this file.

/*******************************************************************************
 *  Math.cpp
 *
 *  (C) 2007 AG Aktives Sehen <agas@uni-koblenz.de>
 *           Universitaet Koblenz-Landau
 *
 *  Additional information:
 *  $Id: $ 
 *******************************************************************************/

#include <limits.h>
#include "Math.h"
#include <math.h>

#include "vec2.h"

#define THIS Math

THIS::THIS()
{
}

THIS::~THIS()
{
}

float THIS::meanAngle( const std::vector<float>& angles )
{
  //calculate vectors from angles
  CVec2 vectorSum(0,0);
  for ( unsigned i=0; i<angles.size(); i++ )
  {
    vectorSum = vectorSum + CVec2( cos( angles[i] ), sin ( angles[i] ) );
  }
  //return vectorSum.getAngle( CVec2(1,0) );
  if ( vectorSum.magnitude() == 0 ) { return 0; }
  return atan2( vectorSum.y(), vectorSum.x() );
}


float THIS::meanAngleWeighted( const std::vector< WeightedValue >& weightedAngles )
{
  //calculate vectors from angles
  CVec2 vectorSum(0,0);
  for ( unsigned i=0; i<weightedAngles.size(); i++ )
  {
    vectorSum = vectorSum + weightedAngles[i].weight * CVec2( cos( weightedAngles[i].value ), sin ( weightedAngles[i].value ) );
  }
  //return vectorSum.getAngle( CVec2(1,0) );
  if ( vectorSum.magnitude() == 0 ) { return 0; }
  return atan2( vectorSum.y(), vectorSum.x() );
}


float THIS::angleVariance( float meanAngle, const std::vector<float>& angles )
{
  float quadSum=0;
  for( unsigned i=0; i < angles.size(); i++ )
  {
    float turnAngle=minTurnAngle( angles[i], meanAngle );
    quadSum += turnAngle*turnAngle;
  }
  return quadSum / float ( angles.size() );
}


float THIS::minTurnAngle( float angle1, float angle2 )
{
/*  CVec2 vector1( cos( angle1 ), sin ( angle1 ) );
  CVec2 vector2( cos( angle2 ), sin ( angle2 ) );
  return vector1.getAngle( vector2 );
  */
  float diff= angle2 - angle1;
  float sign=1;
  if ( diff < 0 ) { sign=-1; }
  //minimal turn angle:
  //if the absolute difference is above 180°, calculate the difference in other direction
  if ( fabs(diff) > M_PI ) {
    diff = 2*M_PI - fabs(diff);
    diff *= sign;
  }
  return diff;
}

Point2D THIS::center( std::vector<Point2D>& points )
{
  double numPoints = double( points.size() );
  double sumX=0, sumY=0;
  for( unsigned i=0; i < points.size(); i++ )
  {
    sumX += points[i].x();
    sumY += points[i].y();
  }
  return Point2D( sumX / numPoints, sumY / numPoints );
}


double THIS::randomGauss(float variance)
{
  if (variance < 0) {
    variance = -variance;
  }
  double x1, x2, w, y1;
  do {
    x1 = 2.0 * random01() - 1.0;
    x2 = 2.0 * random01() - 1.0;
    w = x1 * x1 + x2 * x2;
  } while ( w >= 1.0 );

  w = sqrt((-2.0 * log(w)) / w);
  y1 = x1 * w;
  // now y1 is uniformly distributed
  return sqrt(variance) * y1;
}

double THIS::random01(unsigned long init)
{
  static unsigned long n;
  if (init > 0) {
    n = init;
  }
  n = 1664525 * n + 1013904223;
  // create double from unsigned long
  return (double)(n/2) / (double)LONG_MAX;
}

#undef THIS