A calculation of pi to 127 decimal places in 1719 established Thomas Fantet de Lagny as a significant figure in computational analysis. Although only 112 of these digits proved correct upon later inspection, this numerical approximation held the world record for accuracy for seven decades, reflecting the rigorous, if occasionally fallible, spirit of his mathematical investigations.
Early Education and Career Trajectory
Born in Lyon in 1660, Thomas Fantet de Lagny received his early education at the Fénelon - La Trinité School. His exposure to mathematical texts, specifically works by Georges Fournier and Jacques Pelletier du Mans, fostered an early interest in the field. Following his studies at the University of Toulouse, he relocated to Paris in 1686 to serve as a tutor for the House of Noailles, a role he maintained until 1696. During this period, he engaged in collaborative projects with de l'Hospital and began disseminating his findings through early research papers.
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His formal association with the scientific establishment began in 1695 when he was named an associate of the French Academy of Sciences. Shortly thereafter, in 1697, he transitioned to the Arsenal de Rochefort, where he spent 16 years serving as a professor of hydrography. Upon returning to Paris in 1714, de Lagny occupied various positions, including librarian at the Bibliothèque du roi and deputy director of the Banque Générale between 1716 and 1718. By 1719, his academic standing allowed him to live primarily from a pension awarded by the French Academy of Sciences, where he eventually achieved the rank of pensionnaire in 1723.
Mathematical Contributions and Methodology
De Lagny specialized in analysis and the extraction of roots, producing several foundational texts such as his 1691 work on square and cubic roots and his 1697 introduction to arithmetic and algebra. His 1703 Trignonmétrie française and his 1705 study on the cubature of the sphere expanded his influence within the French mathematical community. His final major publication, Analyse générale, appeared in 1733, the same year he retired from his duties at the academy. He died in Paris in 1734.
Fast facts
- Born: 1660, Lyon
- Died: 1734, Paris
- Field: Mathematical analysis
- Education: Fénelon - La Trinité School
- Affiliation: French Academy of Sciences
- Record: 112 correct decimal places of pi
Questions readers ask
What record did Thomas Fantet de Lagny hold?
He held the record for calculating the most decimal places of pi, with 112 digits verified as correct.
Where did he work during his career?
He served the House of Noailles, the Arsenal de Rochefort, and held various positions at the French Academy of Sciences.
Achievements
- Held posts at French Academy of Sciences, House of Noailles and Arsenal de Rochefort
- Fields: mathematics
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