Based on Instantaneous Trendline, by John Ehlers , identifies the market trend by doing removing cycle component. I think, this simplicity is what makes it attractive :) To understand Ehlers's thought process behind this, refer to the PDF linked below.
hey chuck, did you mean to recursively reference the src variable to feed back into the FIL filter smoother to continually smooth the function forward? i assume so since smoothing h12 on every bar alone doesn't do much, just wondering if this something that Ehlers suggested or something of your own creation since it produces wildly different results depending on how you run the smoother