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

Helsinki Helsinki () is the Capital city, capital and most populous List of cities and towns in Finland, city in Finland. It is on the shore of the Gulf of Finland and is the seat of southern Finland's Uusimaa region. About people live in the municipali ...

) 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. ...

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, ...

during the 1970s. Myrberg received his

PhD A Doctor of Philosophy (PhD, DPhil; or ) is a terminal degree that usually denotes the highest level of academic achievement in a given discipline and is awarded following a course of graduate study and original research. The name of the deg ...

in 1916 at the

University of Helsinki The University of Helsinki (, ; UH) is a public university in Helsinki, Finland. The university was founded in Turku in 1640 as the Royal Academy of Åbo under the Swedish Empire, and moved to Helsinki in 1828 under the sponsorship of Alexander ...

under Ernst Lindelöf 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 mathematician who devised the formula for the Julia set. His works were popularized by Benoit Mandelbrot; the Julia and Mandelbrot fractals are closely related. He founded, ind ...

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 mathematical analysis, analysis. The Fatou lemma and the Fatou set are named aft ...

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 (; ) is a Finnish learned society. It was founded in 1908 and is thus the second oldest academy in Finland. The oldest is the Finnish Society of Sciences and Letters, which was founded in 1838. Member ...

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

References

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