Schmetterer attended lectures by Wolfgang Gröbner, Hans Hornich, Karl Mayrhofer and Karl Strubecker. He formed a close friendship with Edmund Hlawka who was an assistant :-
I frequently had the opportunity to discuss mathematical problems with Hlawka. Even in his early time he was a man who was able to fascinate young students.The university had few students during the war years, and most of them were women. Schmetterer continued to study for his doctorate with Nikolaus Hofreiter, who had been a student of Furtwängler, as his advisor and on 12 July 1941 he was awarded his doctorate for the thesis Approximation komplexer Zahlen durch Zahlen K (i√11) Ⓣ :-
My thesis was concerned with diophantine approximation, at that time an important part of number theory. The great influence of Furtwängler remained for a long time in the Mathematical Institute in Vienna.Schmetterer had been a research assistant from October 1940, but in September 1941, after the award of his doctorate, he had to undertake military service. He served in the Air Force until October 1943 when he was allowed a short holiday and returned to the Mathematical Institute in Vienna. In February 1944 he was sent to the Henschel aircraft factory in Berlin where he worked as a mathematician on aircraft construction. He :-
... was mostly concerned with differential equations in the field of aerodynamics.It is interesting to note that this work brought him into contact with the computer pioneer Konrad Kuse.
After the war ended he spent several weeks in an American internment camp, then was able to return to his assistantship in the Mathematical Institute in Vienna. One advantage of working in the Henschel aircraft factory was the fact that he had to use Fourier series, and now back in the Mathematical Institute he began to study these series more deeply. Johann Radon was appointed to Vienna in 1946, and he influenced strongly the direction of Schmetterer's research. On 21 April 1947 Schmetterer married Elisabeth Schaffer who had been a mathematics student: they had four children, sons George (born 1948), Victor (born 1951) and Leopold (born 1964) and a daughter Eva (born 1955). In 1949 he obtained the right to teach in universities after submitting his Habilitation thesis Über die Approximation gewisser trigonometrischer Reihen Ⓣ on the theory of trigonometrical series.
Schmetterer's interests turned towards probability. He explained in  how this came about:-
In 1948 I was asked by the mathematicians in Vienna to give lectures in probability theory ... The reason was that an old professor of astronomy retired. He had lectured in the field of probability from a standpoint of the theory of errors. ... I did not know anything about probability at this time. So I had to work very hard to be able to instruct students in this field. One year later I was asked by the Technical University in Vienna to give lectures in mathematical statistics ... I did not know anything about mathematical statistics and again I had a very hard time to be able to give lectures in this field which was already very well developed in many countries outside Austria.The outcome of this teaching was Schmetterer's book Einführung in die mathematische Statistik Ⓣ (1956). Harald Cramér, reviewing the text, writes:-
As the author states in his Preface, the lack of a modern text-book on Mathematical Statistics in the German language has made itself felt in an unfortunate way. The present book has grown out of the author's lectures at the University and the Technological Institute of Vienna. It begins with an introductory chapter on Mathematical Probability, well and clearly written though, as the author points out, not designed to give a completely rigorous mathematical treatment. ... As the author states, he is mainly concerned with those classical branches of Mathematical Statistics associated with the names of Fisher, Pearson and, above all, Neyman. ... The treatment is clear and accurate, and takes account of recent developments in statistical theory.It is worth noting that a second German edition appeared in 1966, an English translation in 1974, and a Russian translation in 1976.
On 10 August 1955 he was appointed extraordinary titular professor at the University of Vienna. Then he received an offer of a Chair of Mathematics with special emphasis on mathematical statistics at the University of Hamburg. He took up this post in Hamburg on 1 October 1956, when he was also appointed Director of the Institute of Mathematical Statistics. Realising that Hamburg had large insurance companies which wanted links with his professorship, he gave an inaugural lecture Grundlagen und Probleme der mathematischen Statistik Ⓣ which looked at stochastic processes relevant to risk theory.
Hamburg at this time contained a host of leading mathematicians, and Schmetterer's colleagues included Helmut Hasse, Heinrich Behnke, Wilhelm Blaschke, Ernst Witt, Emil Artin, Emanuel Sperner, Lothar Collatz and Hans Zassenhaus. The famous algebraists in this group were a major influence on Schmetterer who attended lectures by Artin and started research on probability on algebraic structures. He spent the academic year 1958-59 as a research professor at the University of California at Berkeley. Although he enjoyed his year at Berkeley, he turned down the offer of a permanent post there on the grounds that he did not wish to live permanently in the United States. This was not the first offer he had received and rejected. Radon had died in 1956, the year Schmetterer took up his appointment at Hamburg, and in 1957 Schmetterer was offered the chair in Vienna to succeed Radon. He turned this down, as he did an offer from Cologne in 1958. However Vienna again made him an offer in 1960 and this time he accepted, taking up the appointment in the following year :-
Among other reasons, this was due to the fact that all my family, or let me say my parents and the parents of my wife, all stayed in Vienna.Schmetterer was elected to the German Academy of Sciences Leopoldina in 1970, to the Austrian Academy of Sciences in 1971, to the Academy of Sciences of Saxonia in 1983 and to the Academy of Sciences of Bavaria in 1984. He served as secretary general of the Austrian Academy of Sciences from 1975 to 1983. He received many prizes and honours, including the Boltzmann prize, the Schrödinger prize of the Austrian Academy of Sciences, the Medal of Merit Leopoldina as well as an honorary degree from the University of Clermont-Ferrand.
In 1990 Schmetterer retired. His lack of nourishment as a baby caused him eyesight problems which became progressively worse. It his later years he continued to take part fully in the mathematical life of the Institute, despite being unable to read what was written on the blackboard.
His death in 2004 was tragic. He was out walking with his wife and, due to his blindness, she was leading him by the arm in their usual manner. However, she fell and, in order to get help, Schmetterer flagged down a passing car and asked the driver to take him to the nearest village to get assistance. He climbed in the car which set off but minutes later it was hit by a train on an unsafe railway crossing.
Article by: J J O'Connor and E F Robertson
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