Johann Heinrich Rahn

Johann Heinrich Rahn, also known as Hans Heinrich Rahn and Johann Rahn, was a Swiss mathematician, born at Töss in the canton of Zurich on 10 March 1622 and dying on 27 May 1676, who is credited with the first use of the division sign and of the therefore sign. The symbols appeared in his Teutsche Algebra of 1659, written with the collaboration of John Pell, and it is uncertain whether Rahn or Pell introduced them. The book contains an example of the Pell equation and is the first German-language presentation of the algebraic theories of Viète and Descartes. A member of a prominent burgher family of Zurich, he sat on its councils and held several public offices, including Landvogt of Kyburg and head of the arsenal. John Pell, Cromwell's representative in Zurich, introduced him to algebra between 1654 and 1658, and Thomas Brancker's English translation of 1668 brought the work wide circulation.