Maths.h

#ifndef CARMA_PHASEMONITOR_MATHS_H
#define CARMA_PHASEMONITOR_MATHS_H

/* $Id: Maths.h,v 1.3 2006/06/26 08:45:16 colby Exp $ */

#include <math.h>

namespace carma
{
  namespace phasemonitor
  {

    class Maths
    {
      public: 
        static double mean( time_t *x, int n )
        {
          float Sx = 0.0;

          for ( int i = 0; i < n; i++ )
            Sx += x[i];

          return (double)( Sx / (double)n );
        }

        static double mean( float *x, int n )
        {
          float Sx = 0.0;

          for ( int i = 0; i < n; i++ )
            Sx += x[i];

          return (double)( Sx / (double)n );
        }

        static double mean( double *x, int n )
        {
          double Sx = 0.0;

          for ( int i = 0; i < n; i++ )
            Sx += x[i];

          return ( Sx / (double)n );
        }

        static void fitLine( float *x, float *y, int n, float &a, float &b )
        {
          double Sx, Sy, Sxx, Sxy; 

          Sx = Sy = Sxx = Sxy = 0.0;

          for ( int i = 0; i < n; i++ )
          {
            Sx  += (double)x[i];
            Sy  += (double)y[i];
            Sxx += (double)x[i] * (double)x[i];
            Sxy += (double)x[i] * (double)y[i];
          }

          Sx  /= (double)n;
          Sy  /= (double)n;
          Sxx /= (double)n;
          Sxy /= (double)n;

          if (n == 1)
          {
            a = 0.0 ; 
            b = y[0] ;
          }
          else
          {
            a = (float)((Sxy - Sx * Sy) / (Sxx - Sx * Sx));
            b = (float)((Sxx * Sy - Sx * Sxy) / (Sxx - Sx * Sx));
          }

        }

        static float rms( float *x, int n )
        {
          float Sx, Sxx;

          Sx = Sxx = 0.0;

          for ( int i = 0; i < n; i++ )
          {
            Sx  += x[i];
            Sxx += x[i] * x[i];
          }

          Sx  /= (float)n;
          Sxx /= (float)n;

          return ( sqrtf(Sxx - Sx*Sx) );
        }

    }; // Class Maths
  } // namespace phasemonitor
} // namespace carma
#endif // CARMA_PHASEMONITOR_MATHS_H