RSI

Overview of the Relative Strength Index calculation.

The relative strength index (RSI) is a technical indicator of momentum that measures the speed and change of price on a scale of 0 to 100, typically over the past 14 periods. Readings over 70 are considered overbought while readings below 30 are considered oversold.

The source code for the RSI function is available here.

/* Often documentation present the RSI calculation as follow:
 *    RSI = 100 - (100 / 1 + (prevGain/prevLoss))
 *
 * The following is equivalent:
 *    RSI = 100 * (prevGain/(prevGain+prevLoss))
 *
 * The second equation is used here for speed optimization.
 */