Fast Trend Line Momentum (FTLM) and Slow Trend Line Momentum (SLTM) indicators show the rate of price change, FATL and SATL are calculated the similar way as Momentum indicator:

FTLM(bar) = FATL(bar) – RFTL(bar)
STLM(bar) = SATL(bar) – RSTL(bar)

where:

FATL(bar) - FATL digital filter;
RFTL(bar) - RFTL digital filter;
SATL(bar) - SATL digital filter;
RSTL(bar) - RSTL digital filter;

The main difference FTLM from the classic Momentum indicator is the following: it uses the close prices, processed by digital fiters instead of close prices itself. As a result, FTLM looks smoothed and regular, in contrast with classic Momentum technical indicator.