🚀 go-pugleaf

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> -----------------------------------------
> \subsection{The Quartic AGM: by J.M.Borwein and P.B.Borwein}
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> $$a_{n+1} := \frac{a_n + b_n}{2}$$
> $$b_{n+1} := \sqrt[4]{\frac{a_n b_n (a_n^2 + b_n^2)}{2}}$$
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> 
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> $$\pi_n = \frac{2 a_{n+1}^4}{\displaystyle 1-\sum_{k=0}^{n} 4^n[a_k^4 - (\frac{a_k^2 + b_k^2}{2})^2]}$$
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> -----------------------------------------

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---------------------------
Ryuji Matsumoto
Kyushu Institute of Technology.(Japan)
e-mail:matumoto@pluto.ai.kyutech.ac.jp