MACD Signal Line
MACDS(len1, len2, len3)
len1 - faster moving average period (typically 13)
len2 - slower moving average period (typically 26)
len3 - signal smoothing period (typically 9)
MACDS is an EMA-smoothed version of MACD.
This is also know as the "signal line".
It is calculated as EMA(MACD(len1,len2),len3).
This indicator supports ultra-fast one-pass calculation when used in the Data Section with non-variable lengths.