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sxy_series_linear.cpp

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// =======================================================================

char* series_linear_cpp = "$Id: sxy_series_linear.cpp,v 1.3 2002/11/28 21:01:01 clinio Exp $";

// =======================================================================

#include <float.h>
#include "sxy_series_linear.h"

// =======================================================================

// .......................................................................

SXYLinearSeries::SXYLinearSeries(unsigned int buffer_size, 
unsigned int resolution) : 
SXYCoeficientsAproximationSeries(2, buffer_size, resolution) { 
}

// .......................................................................

SXYLinearSeries::~SXYLinearSeries(void) {
}

// .......................................................................

unsigned int SXYLinearSeries::aproxFunctionCallback( double x, double& y ) {
   double A, B;
   if (!getCoeficient(0, A) || !getCoeficient(1, B) ) return 0;
   y = A*x + B;
   return 1;
}

// .......................................................................
unsigned int SXYLinearSeries::calculateCoeficients(unsigned int n, 
double* buffer_x, double* buffer_y) {
   double sxx = 0, sx = 0, sy = 0, sxy = 0, syy = 0;

   // Teste de ausência de pontos suficientes */
   if ( n <= 1 ) return 0;

   for ( unsigned int i = 0; i < n; i++ ) { 
      double x = buffer_x[i];
      double y = buffer_y[i];

      sx = sx + x;
      sy = sy + y;
      sxx = sxx + (x * x);
      sxy = sxy + (x * y);
      syy = syy + (y * y);
   }

   // Teste de uma reta tendendo a verticalidade*/
   if (fabs( ((double)n)*sxx -sx*sx) < 1e-10) return 0;

   double A = ( ((double)n)*sxy-sx*sy ) / ( ((double)n)*sxx-sx*sx );
   double B = (sy-A*sx)/((double)n);

   setCoeficient(0,A);
   setCoeficient(1,B);

   return 1;
}

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SXY
Tecgraf / PUC-Rio - Computer Graphics Technology Group