code: public static double simpleMovingAverageQuick(double Yt, double YtminusN, double Ft, int N) {
          double SMA=(Yt-YtminusN)/N+Ft;
  
          return SMA;
      }
docs: Simple Moving Average: Calculates Ft+1 by using previous results. A quick version of the simpleMovingAverage
  
  @param Yt
  @param YtminusN
  @param Ft
  @param N
  @return