Hello everybody!
I'm layman in physics and new in this forum, but recently I feel very strong interest in physics... and now I am struggling to obtain some knowledge. That's why i decided to sign up in the forum and I hope to get help from people who are versed and educated in physics.

Here is the first question which I hope to solve....
I know about the notorious formulation: p = mv
p - momentum;
m - mass;
v - velocity.

So far, so good...

Two weeks ago, I read a text, where the author talks about "free movement (circulation) in gravitational orbit" and he (the author) describes the momentum like this: p = miv/(2πl) = const
p - momentum;
iv - orbital velocity (velocity of circulation);
2πl - orbital length (perimeter of circumference).

After that, he says:
when we have 2πl= i (imaginary number), we get: p = mv (the notorious formulation)

I can't grasp his idea... I searched all the google and and all the textbooks, which i have at home... but i can't find information about the author's primary formulation: p = miv/(2πl) = const

I can't post the original text, because it is written in bulgarian. the literal translation will be difficult for me. English is not my native language, but i hope I asked my question clearly... So I am looking for some comments, which will explain me the formulation... I will be very thankful for every explanation....

Have a nice day!