Cornelius Lanczos

"Lanczos" redirects here. For resampling method, see Lanczos resampling.

Cornelius Lanczos
Born	(1893-02-02)February 2, 1893 Székesfehérvár
Died	Budapest
Nationality	Hungarian
Fields	Mathematics Theoretical physics
Alma mater	University of Szeged
Doctoral advisor	Rudolf Ortvay
Other academic advisors	Loránd Eötvös, Leopold Fejér, Franz Himstedt, Erwin Madelung
Notable awards	Chauvenet Prize (1960)

Cornelius (Cornel) Lanczos (Hungarian: Lánczos Kornél, pronounced [ˈlaːnt͡soʃ ˈkorneːl], until 1906: Löwy (Lőwy) Kornél) was a Jewish Hungarian mathematician and physicist, who was born on February 2, 1893, and died on June 25, 1974.

He was born in Székesfehérvár to Karl Löwy (Lőwy Károly) and Adél Hahn.

Lanczos' Ph.D. thesis (1921) was on relativity theory. In 1924 he discovered an exact solution of the Einstein field equation, which represents a cylindrically symmetric rigidly rotating configuration of dust particles. This was later rediscovered by Willem Jacob van Stockum and is known today as the van Stockum dust. It is one of the simplest known exact solutions in general relativity, and is regarded as an important example, in part because it exhibits closed timelike curves. Lanczos served as assistant to Albert Einstein during the period of 1928–29.

He did pioneering work along with G.C. Danielson on what is now called the fast Fourier transform (FFT, 1940), but the significance of his discovery was not appreciated at the time, and today the FFT is credited to Cooley and Tukey (1965). (As a matter of fact, similar claims can be made for several other mathematicians, including Carl Friedrich Gauss.)

Working in Washington DC at the U.S. National Bureau of Standards after 1949, Lanczos developed a number of techniques for mathematical calculations using digital computers, including:

• the Lanczos algorithm for finding eigenvalues of large symmetric matrices.
• the Lanczos approximation for the gamma function.
• the conjugate gradient method for solving systems of linear equations

In 1962, Lanczos showed that the Weyl tensor, which plays a fundamental role in general relativity, can be obtained from a tensor potential which is now called the Lanczos potential.

Lanczos resampling is based on a windowed sinc function as a practical upsampling filter approximating the ideal sinc function. Lanczos resampling is widely used in video up-sampling for digital zoom applications.

Lanczos was an outstanding physics teacher. Books such as The Variational Principles of Mechanics (1949) show his explanatory ability and enthusiasm for the subject.

During the McCarthy era, Lanczos came under suspicion for possible Communist links. In 1952, he left the U.S. and moved to the School of Theoretical Physics at the Dublin Institute for Advanced Studies in Ireland, where he succeeded Schrödinger and stayed until 1968. When at D.I.A.S. he wrote the classic book, "Applied Analysis" (1956).

According to a short speech delivered Oct 1, 2010 during Lanczos' induction to the NIST Portrait Gallery of Distinguished Staff, his daughter-in-law, Alice Lanczos, described his return to Hungary in 1939 from his then-position at Purdue University, when he attempted to convince his family to return to the US with him due to the anti-Jewish Nazi threat. His wife was too ill to travel, and died several weeks later from tuberculosis. He was only able to extricate his 5-year-old son and return to the US just before the war began. When the Nazis purged Hungary of Jews in 1944, only his sister and a nephew survived. That son married, moved to Seattle and raised two sons. When his son Elmar looked at his own firstborn son he said "For me, it proves that Hitler did not win."

Publications

Books

• (22 pages, S. Brodetsky Memorial Lecture)

References

• Barbara Gellai (2010) The Intrinsic Nature of Things: the life and science of Cornelius Lanczos, American Mathematical Society ISBN 978-0-8218-5166-1 .

External links

• .
• Cornelius Lanczos at the Mathematics Genealogy Project
• Cornelius Lanczos, Collected published papers with commentaries, published by North Carolina State University
• Photo gallery of Lanczos by Nicholas Higham
• Series of historic video tapes produced in 1972, digitalized on the occasion of the 120th anniversary of Cornelius Lanczos's birth