Triple EMA: 3 * ema1 - 3 * ema2 + ema3, which cancels the lag of a linear trend exactly rather than merely reducing it.

Three chained EMAs, each running over a series that is already na for its own warmup, so the first printed bar is 3 * length - 3 and not length - 1 (see emaOfGapped). close is hard-coded in the reference, so there is no source setting.

The three terms are added left to right, as the definition writes them, not regrouped as 3 * (ema1 - ema2) + ema3: the two round differently in the last digits, and the grouped form can hide an overflowing term. Any absent term, or a sum that is not finite, leaves the bar absent (nulls).