Relative Strength show the quotient (ratio) between a numerator (Your Security) and a common denominator (SPX, BTC, ...).
I inspired myself from already established indicators. But I've made my own because I had some issues with others.
Sometimes the moving average weren't fixed but where floating through the window.
Sometimes the colors (Up, Down) were inaccurate because the compiler didn't notice infinitesimal changes (0.0001 > 0.0002)
Thanks.
(The Relative Strength indicator is at the top of the chart.)