The indicator of smoothed Standard Deviation or by the terminology of the resulting indicator's author — the base volatility indicator.
The indicator uses SmoothAlgorithms.mqh library classes (copy it to <terminal_data_folder>\MQL5\Include). The use of the classes was thoroughly described in the article "Averaging Price Series for Intermediate Calculations Without Using Additional Buffers".
Originally this indicator has been written in MQL4 and was first published in the Code Base on 21.12.2015.
Figure 1. The BaseVolatility indicator
Translated from Russian by MetaQuotes Software Corp.
Original code: https://www.mql5.com/ru/code/14727
The Acceleration/Deceleration Indicator (AC) measures acceleration and deceleration of the current driving force.Average Directional Movement Index (ADX)
The Average Directional Movement Index Indicator (ADX) helps to determine if there is a price trend.