Webby's RSI

Mike Webster's RSI (Really Simple Indicator), aka Webby's RSI .
This script is a PineScript port of John Muchow's ThinkScript port.

This indicator useful during an uptrend to gauge the general market trend. It is used against leading market indexes like Nasdaq.
It tracks day low against 21d ema. Day low above 21d ema and above in the range of 0.5% to 2% is considered as normal and positive.
During the initial days of an uptrend, above 2% is considered positive and strong uptrend but not during the late stage of the uptrend. Below 21d ema, the uptrend may be under pressure, and caution is recommended.