f * X + ( 1.0 - f ) * Y
X = Time Series
Y = Exponential Moving Average one period ago (1st period Y is set to 1st period X)
f = 2 / (ExpAvg Periods + 1)
Provides a smoothing of a time series with an emphasis given to values during the most recent time periods. Most users are more comfortable working with time periods rather than percentages, therefore as a general guideline, the ExpAvg Factor roughly translates to the number of days that the function takes into consideration. However, in reality it takes all previous days into consideration, while giving the first day an exponentially smaller input to the most recent value.