Niels Erik Nørlund (26 October 1885, in Slagelse – 4 July 1981, in Copenhagen) was a Danish mathematician. His book Vorlesungen über Differenzenrechnung (1924, reprinted 1954) was the first book on complex function solutions of difference equations. His doctoral students include Georg Rasch. The Norlund Alps and Norlund Land in Greenland were named after him. He was also the brother of Margrethe Nørlund Bohr and brother-in-law of Nobel Prize winning physicist Niels Bohr. Selected works with René Lagrange as editor: See also Nörlund–Rice integral Inge Lehmann References Further reading Mathematics and Mathematicians: Mathematics in Sweden Before 1950 Nørlund on Calculus of Differences 20th-century Danish mathematicians Foreign Members of the Royal Society People from Slagelse 1885 births 1981 deaths Academic staff of the University of Copenhagen Rectors of the University of Copenhagen