John Machin
John Machin  

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John Machin


Born  c. 1686 England 
Died  9 June 1751 (aged 70–71) London, England 
Nationality  English 
Fields  Mathematician and astronomer 
Institutions  Gresham College 
Notable students  Brook Taylor 
Known for  Machinlike formula 
John Machin (bapt. c. 1686 – June 9, 1751),^{[1]} a professor of astronomy at Gresham College, London, is best known for developing a quickly converging series for Pi in 1706 and using it to compute Pi to 100 decimal places.
History
John Machin served as secretary of the Royal Society from 1718 to 1747. He was also a member of the commission which decided the Calculus priority dispute between Leibniz and Newton in 1712.^{[2]}
On 16 May 1713 he succeeded Alexander Torriano as professor of astronomy in Gresham College, and held the post until his death, which occurred in London on 9 June 1751. Machin enjoyed a high mathematical reputation. His ingenious quadrature of the circle was investigated by Hutton, and in 1706 he computed the value of π by Halley's method to one hundred decimals places. A mass of his manuscripts is preserved by the Royal Astronomical Society; and writing to William Jones in 1727, he asserted his claim to the parliamentary reward of £10,000 for amending the lunar tables.^{[2]}
In 1728, he was listed as one of the subscribers to the Cyclopaedia of Ephraim Chambers.^{[3]}
Formula
Machin's formula^{[4]} (for which the derivation is straightforward) is:
The benefit of the new formula, a variation on the Gregory/Leibniz series (Pi/4 = arctan 1), was that it had a significantly increased rate of convergence, which made it a much more practical method of calculation.
To compute Pi to 100 decimal places, he combined his formula with the Taylor series expansion for the inverse tangent. (Brook Taylor was Machin's contemporary in Cambridge University.) Machin's formula remained the primary tool of Pihunters for centuries (well into the computer era).
Several other Machinlike formulae are known.
See also
References
Part of a series of articles on the 
mathematical constant π 

Uses 
Properties 
Value 
People 
History 
In culture 
Related topics 
 ↑ Anita McConnell, ‘Machin, John (bap. 1686?, died 1751)’, Oxford Dictionary of National Biography, Oxford University Press, 2004. Accessed 26 June 2007. doi:10.1093/ref:odnb/17533
 ↑ ^{2.0} ^{2.1} Clerke 1893.
 ↑ List of Subscribers to the Cyclopaedia at library.wisc.edu
 ↑ Machin's Formula at MathWorld
Attribution
 This article incorporates text from a publication now in the public domain: Clerke, Agnes Mary (1893). "Machin, John (d.1751)". In Lee, Sidney. Dictionary of National Biography. 35. London: Smith, Elder & Co.<templatestyles src="Module:Citation/CS1/styles.css"></templatestyles>
External links
Works written by or about John Machin at Wikisource
 O'Connor, John J.; Robertson, Edmund F., "John Machin", MacTutor History of Mathematics archive, University of St Andrews<templatestyles src="Module:Citation/CS1/styles.css"></templatestyles>.