In the heavily cited paper by Harris 1978, there is a section on "Overlap Correlation" where he's using a "fractional overlap r" in his equation. Here is a screen shot from the open source paper linked above:
Can someone please help explain what's going on here? I'm trying to use equation 17 but I don't understand what the indices represent. How can "r" be a fraction? If the summation is taking place over integer values, then the term "rN" is an integer, which in general means that "r" must be an integer. He gives some diagrams, but those don't really help.