English

Algorithmic determination of a large integer in the two-term Machin-like formula for pi

General Mathematics 2021-09-14 v3

Abstract

In our earlier publication we have shown how to compute by iteration a rational number u2,k{u_{2,k}} in the two-term Machin-like formula for pi of kind π4=2k1arctan(1u1,k)+arctan(1u2,k),kZ,k1,\frac{\pi}{4}=2^{k-1}\arctan\left(\frac{1}{u_{1,k}}\right)+\arctan\left(\frac{1}{u_{2,k}}\right),\qquad k\in \mathbb{Z},\quad k\ge 1, where u1,k{u_{1,k}} can be chosen as an integer u1,k=ak/2ak1{u_{1,k}} = \left\lfloor{{a_k}/\sqrt{2-a_{k-1}}}\right\rfloor with nested radicals defined as ak=2+ak1{a_k}=\sqrt{2+a_{k-1}} and a0=0a_0 = 0. In this work we report an alternative method for determination of the integer u1,ku_{1,k}. This approach is based on a simple iteration and does not require any irrational (surd) numbers from the set {ak}\left\{a_k\right\} in computation of the integer u1,ku_{1,k}. Mathematica programs validating these results are presented.

Keywords

Cite

@article{arxiv.2107.01027,
  title  = {Algorithmic determination of a large integer in the two-term Machin-like formula for pi},
  author = {Sanjar M. Abrarov and Rajinder K. Jagpal and Rehan Siddiqui and Brendan M. Quine},
  journal= {arXiv preprint arXiv:2107.01027},
  year   = {2021}
}

Comments

30 pages

R2 v1 2026-06-24T03:50:31.321Z