Joseph Knar

Joseph Knar (January 1, 1800 – June 1, 1864) was an Austrian mathematician working at the University of Graz.He is most well known for discovering Knar's formula, an infinite product formula involving the gamma function.

From a poor family, Knar graduated from the University of Graz at the age of 19 after studying mathematics and law.In 1821, he became a full professor, a position which he held until his death from a stroke in 1864.He published several books including a two-volume textbook Lehrbuch der Elementarmathematik on elementary mathematics.

Knar's most famous mathematical contribution was his discovery of the infinite product formula

${\displaystyle \Gamma (1+x)=2^{2x}\prod _{n=1}^{\infty }{\frac {\Gamma ({\frac {1}{2}}+2^{-n}x)}{\sqrt {\pi }}}}$

for ${\displaystyle x>0}$.

• Neues, sehr einfaches Verfahren zur Ausziehung der Wurzeln aus bestimmten Zahlen (1824)
• Lehrbuch der Elementarmathematik, 2 volumes (1828–1829)
• Theorie der harmonischen Reihen in Archiv der Mathematik und Physik (1864)