SmartQuant Discussion

   protected void Add( double x, double y ) {
      //Console.WriteLine( "add,{0},{1:#.00},{2:#.000}", dsSlope.Name, val, x );
      SumXX += x * x;
      SumX  += x;
      SumXY += x * y;
      SumY  += y;
      SumYY += y * y;
      Xcnt++;
   }
   
   protected void Remove( double x, double y ) {
      //Console.WriteLine( "rem,{0},{1:#.00},{2:#.000}", dsSlope.Name, val, x );
      SumXX -= x * x;
      SumX  -= x;
      SumXY -= x * y;
      SumY  -= y;
      SumYY -= y * y;
      Xcnt--;
       
      CanCalcSlope = true;
   }

   protected virtual void CalcStats() {
       
      double oldb1 = b1;
       
      Sxx = SumXX - SumX * SumX / Xcnt;
      Sxy = SumXY - SumX * SumY / Xcnt;
      Syy = SumYY - SumY * SumY / Xcnt;

      SST = Syy;
      SSR = Sxy * Sxy / Sxx;
      SSE = SST - SSR;

      RR = SSR / SST;
      R = Sxy / Math.Sqrt(Sxx * Syy);
         
      SD = Math.Sqrt( Syy / ( Xcnt - 1 ) );

      meanY = SumY / Xcnt;
       
      b1 = CanCalcSlope ? Sxy / Sxx : 0;
      b0 = ( 1 / Xcnt ) * ( SumY - b1 * SumX );
      b2 = b1 - oldb1;  // *** do this differently
   }