Ludolph van Ceulen
|Ludolph van Ceulen|
28 January 1540|
Hildesheim, Bishopric of Hildesheim, Holy Roman Empire
|Died||31 December 1610
Leiden, Dutch Republic
|Notable students||Willebrord Snellius
Frans van Schooten, Sr.
|Known for||Ludolphine number|
Ludolph van Ceulen (German: [fan ˈkɔʏlən], Dutch: [vɑn ˈkøːlən] or [fɑn ˈkøːlən]; 28 January 1540 – 31 December 1610) was a German-Dutch mathematician from Hildesheim. He emigrated to the Netherlands.
Ceulen moved to Delft to teach fencing and mathematics. In 1594 he opened a fencing school in Leiden. In 1600 he was appointed the first professor of mathematics at Leiden University. He died in Leiden.
Calculating π 
Ludolph van Ceulen spent a major part of his life calculating the numerical value of the mathematical constant π, using essentially the same methods as those employed by Archimedes some seventeen hundred years earlier. He published a 20-decimal value in his 1596 book Van den Circkel ("On the Circle"), later expanding this to 35 decimals. After his death, the "Ludolphine number",
was engraved on his tombstone in Leiden. The tombstone was later lost but was restored in 2000.
- Ludolph van Ceulen at the Mathematics Genealogy Project
- "Digits of Pi" by Barry Cipra (includes photo of tombstone)
- Oomes, R. M. Th. E.; Tersteeg, J. J. T. M.; Top, J. "The epitaph of Ludolph van Ceulen." Nieuw Arch. Wiskd. (5) 1 (2000), no. 2. online (Dutch)
- MacTutor biography of van Ceulen
- "Ludolph van Ceulen (1540-1610)" (in Dutch). Archived from the original on 5 May 2006. Retrieved 31 March 2008.