I want to set up a 15 -day cycle moving average. Which master can teach?

Generally, the default is 5, 15, 30, and 60 minutes, as well as the day, Zhou, Month, season, and year. Want to increase the 15 -day cycle.
is the 15 -day cycle line. It is not a 15 -day moving average in the daily line. The latter I will.