(b. Berlin, Germany, 22 July 1882; d. Annecy, France, 20 April 1957)
After one semester at the University of Lausanne in 1901, Knopp returned to Berlin to study at its university. He passed the teacher’s examination in 1906 and received the Ph.D. in 1907. In the spring of 1908 he went to Nagasaki to teach at the Commercial Academy; he also traveled in China and India. In the spring of 1910 he returned to Germany, where he married the painter Gertrud Kressner. They moved to Tsingtao, where Knopp taught at the German-Chinese Academy. Back in Germany in 1911, he received his habilitation at Berlin University while teaching at the Military Technical Academy and at the Military Academy. An officer in the German army, he was injured early in World War I. In the fall of 1914 Knopp resumed teaching at Berlin University, in 1915 he became extraordinary professor at Koingsberg University and in1919 ordinary professor. In 1926 he was appointed to Tubingen University, where he remained until retiring in 1950.
Knopp was a specialist in generalized limits. He not only contributed many details but also clarified the general concept and the aims of the theory of generalized limits. He is well known for his extremely popular books on complex functions, which have often been republished and translated. He was responsible for the sixth through tenth editions of H. von Mangoldt’s popular Einführung in die höhere Mathematik. He was a cofounder of Mathematische Zeitschrift in 1918 and from 1934 to 1952 was its editor.
Knopp’s writings include Grenzwerte von Reihen bei der Annāherung on die Konvergenzgrenze (Berlin, 1907), his diss,; “Neuere Untersuchungen in der Theorie der diver- genten Reihen”, in Jahresbericht der Deutschen Mathematiker - Veringung,32 (1923), 43-67; “Zur Theorie der Limitierungsverfahren I. II”, in Mathematische Zeitschrift,31 (1929), 97-127, 276-305; Theorie und Anwendung der unendlichen Reihen, which is Grundlehren der mathematischen Wissensfchaften, II, 4th ed.(Berlin, 1947); Funktionentheorie, 2 vols., which is Sammlung Goschen, nos. 668 and 703, 9th ed. (Berlin, 1957); Aufgabensammlung zur Funktionentheorie, 2 vols., which is Sammlung Goschen, nos.887and 878, 5th ed. (Berlin 1957-1959); and Elementeder Funktionentheorie, which is Sammlung Goschen, no. 1109, 7th en. (Berlin, 1966).
An obituary is E. Kamke and K. Zeller, “Konrad Knopp †”, in Jahresbericht der Deutschen Mathematiker-Vereinigung, 60 (1958), 44-49.