Pekka Juhana Myrberg (30 December 1892, Viipuri – 8 November 1976,

Helsinki Helsinki ( or ; ; sv, Helsingfors, ) is the Capital city, capital, primate city, primate, and List of cities and towns in Finland, most populous city of Finland. Located on the shore of the Gulf of Finland, it is the seat of the region of U ...

) was a Finnish mathematician known for developing the concept of

period-doubling bifurcation In dynamical systems theory, a period-doubling bifurcation occurs when a slight change in a system's parameters causes a new periodic trajectory to emerge from an existing periodic trajectory—the new one having double the period of the original. W ...

in a paper published in the 1950s. The concept was further developed by

Mitchell Feigenbaum Mitchell Jay Feigenbaum (December 19, 1944 – June 30, 2019) was an American mathematical physicist whose pioneering studies in chaos theory led to the discovery of the Feigenbaum constants. Early life Feigenbaum was born in Philadelphia, Pen ...

during the 1970s. Myrberg received his PhD in 1916 at the

University of Helsinki The University of Helsinki ( fi, Helsingin yliopisto, sv, Helsingfors universitet, abbreviated UH) is a public research university located in Helsinki, Finland since 1829, but founded in the city of Turku (in Swedish ''Åbo'') in 1640 as the ...

under

Ernst Lindelöf Ernst is both a surname and a given name, the German, Dutch, and Scandinavian form of Ernest. Notable people with the name include: Surname * Adolf Ernst (1832–1899) German botanist known by the author abbreviation "Ernst" * Anton Ernst (1975- ...

with thesis ('On the theory of the convergence of Poincaré's series'). He began his career by teaching at a gymnasium, and then became professor extraordinarius at the University of Helsinki in 1921 and professor ordinarius in 1926. In 1952 he became the rector and then served as the chancellor of the University of Helsinki from 1952 to 1962. In 1962 he retired as professor emeritus but continued publishing mathematical papers into the 1970s. In the 1950s, Myberg published several fundamental papers on the

iteration Iteration is the repetition of a process in order to generate a (possibly unbounded) sequence of outcomes. Each repetition of the process is a single iteration, and the outcome of each iteration is then the starting point of the next iteration. ...

of rational functions (especially quadratic functions).some of Myrberg's publications online
''Annales Acad. Sci. Fennicae'' 1958, 1959, 1963, ''J. Math. Pures Appliquées'' 1962 His research revived interest in the results of

Gaston Julia Gaston Maurice Julia (3 February 1893 – 19 March 1978) was a French Algerian mathematician who devised the formula for the Julia set. His works were popularized by French mathematician Benoit Mandelbrot; the Julia and Mandelbrot fractals are cl ...

and

Pierre Fatou Pierre Joseph Louis Fatou (28 February 1878 – 9 August 1929) was a French mathematician and astronomer. He is known for major contributions to several branches of analysis. The Fatou lemma and the Fatou set are named after him. Biography P ...

published during the beginning of the 20th century. Myberg was a member of the

Finnish Academy of Sciences The Finnish Academy of Science and Letters (Finnish ''Suomalainen Tiedeakatemia''; Latin ''Academia Scientiarum Fennica'') is a Finnish learned society. It was founded in 1908 and is thus the second oldest academy in Finland. The oldest is the Fi ...

. In 1954 he was an invited speaker (''Über die Integration der Poissonschen Gleichung auf Riemannschen Flächen'') at the International Mathematical Congress in Amsterdam.

References

External links

* 1892 births 1976 deaths Finnish mathematicians {{Europe-mathematician-stub