Overview of the Exponential Moving Average indicator.
EMA
An exponential moving average (EMA) is the weighted average of a set of data points where new data points receive greater weight in the average calculation. An exponential moving average is a technical indicator of a trend that responds faster to new data points than a simple moving average because a multiplier is used to give preference to the new data points and reduce lag in responsiveness to price movements.
The source code for the EMA function is available here.