Quick and easy instructions for calculating the daily trend from weight are given above on page . That calculation uses a particular exponentially smoothed moving average chosen for ease of calculation as well its effectiveness in extracting the trend from daily weights. This section presents the mathematical definition of all the forms of moving averages described in chapter . You don't have to understand this material to understand moving averages, and it's certainly not necessary to use moving averages to control your weight. If you're interested in experimenting on your own with moving averages on a computer, these equations provide the foundation for the programs you'll write.
All moving averages operate on a time series of measurements, M1, M2,..., Md, where d is the total number of measurements made to date and Md is the most recently made measurement. For convenience in the discussion, we'll assume one measurement is made per day; any other regular interval is equivalent.