
Re: A single term formula for calculating the circumference of ellipse
Posted:
Jun 14, 2009 1:31 PM


Shahram Zafary <shahram_zafary@yahoo.com> wrote: > Hello dear Mr. Cantrell. > Thanks a lot, for your really exact comments on my formula. > I am really grateful and hope you permit me contact you again about this > formula and some same findings that I found out before
Dear Mr. Zafary,
You are certainly welcome to contact me using my sigmaxi.net email address.
I mentioned your nice formula to Gerard Michon recently, and he has now added a section about it on his Numericana site. See
<www.numericana.com/answer/ellipse.htm#zafary>.
Note that Gerard found a very nice alternative way of writing your approximation: The quantity h = ((a  b)/(a + b))^2 often appears in dealing with the perimeter of an ellipse. Using h, your approximation can be written simply as
pi (a + b) (4/pi)^h
Although I really liked your approximation before, I like it even more in the form above!
Best regards, David

