The data points seem not to all lie exactly on the circumference of a circle.soheil_hooshdaran wrote: ↑Tue Feb 02, 2021 8:10 pmThe author said:

Exactly a narrow band must be dragged around the circle

and when asked where does the band come from, he replied:

"a small constant coefficient multiplied by the circle's radius"

The 'author' probably requires them to be contained in a wider but narrow band (circular bar) with the circumference as one edge of the band (bar).

Once all the data points are within the required narrow band (bar) their circular mean can be calculated accordingly.