Relative Strength based on a fixed reference session date. This study works on day timeframe only.
The idea here is to "fix" a reference trading session day. The relative strength of subsequent candles are measured based on this reference day only. Relative strengths of bars before this bar is irrelevant and not plotted. As the plotting of the bars advances, the length is automatically adjusted so that the base reference is the "fixed" reference only. The RS value is multiplied by 100 to give a percentage value.
The other Relative Strength indicators that I have published (and other Relative Strength scripts generally available on TradingView), generally take a fixed length as input and that has to be advanced each trading session. What this results into is that only the "latest bar" RS is compared to the "reference" session date. All the RS values prior to this latest bar is actually compared to days previous to the reference date.
In the example above, we have input 13-Feb-2020 as the "fixed" reference trading session day. Starting from 14-Feb-2020, each session day, we calculate the RS always with respect to 13-Feb-2020, unlike the other scripts. When the RS value of today, 08-Sep-2020 is being calculated, it is using 13-Feb-2020 (as the other scripts do when the length is advanced one day each trading session day). However, when the RS value of 07-Sep-2020 is being calculated today (08-Sep-2020), it is still using 13-Feb-2020 as the reference. In the other scripts, a calculation of RS for 07-Sep-2020 on 08-Sep-2020 would have taken 12-Feb-2020 as the reference value.
This plot thus gives the exact performance of the script with respect to the benchmark index from the fixed reference each day. A performance trend is therefore possible to do on this plot.