The triangular moving average (TMA) is a weighted average of the last n prices (P), whose result is equivalent to a double smoothed simple moving average (i.e. calculated twice).
As with other moving averages, the triangular moving average can be used to identify a trend by using the slope of the average (or lack of slope in a ranging market). However, due to the additional smoothing, triangular moving averages tend to be smoother, and have more waves, than standard moving averages. Interestingly, triangular moving averages often appear more responsive to direction changes, even though the additional smoothing actually moves the domainant input value to the middle of the input series (which would decrease responsiveness).