Germund Dahlquist

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Germund Dahlquist (born January 16, 1925 in Uppsala , † February 8, 2005 in Stockholm ) was a Swedish mathematician in the field of numerical mathematics . He made pioneering contributions to the theory of the numerical solution of initial value problems , especially to the topic of stability .

Life

His career as an applied mathematician, as well as his preoccupation with stability , began in 1949 at Matematikmaskinnämnden , where he worked with the Swedish computer BESK and made weather forecasts.

Dahlquist received his PhD from Stockholm University in 1958 on Stability and Error Bounds in the Numerical Integration of Ordinary Differential Equations . Here he introduced the logarithmic norms and also proved the first Dahlquist barrier using linear multistep methods . His supervisor was Fritz Carlson , Lars Hörmander the second reviewer.

In 1963 he became a professor at the Royal Technical University of Stockholm in the first Swedish numerics chair, where he set up the numerics institute NADA. Dahlquist held this chair until his death. During his career he had 31 PhD students.

In the same year he published his paper in which he introduced A-stability , one of the most cited publications in numerical mathematics. The article also contains a proof of the second Dahlquist barrier , which states that an A-stable linear multistep method can never be of order higher than two.

In 1975 he introduced the term G-stability, which allowed the non-linear stability analysis of the Runge-Kutta method .

In 1978, Dahlquist published a new proof of the second Dahlquist barrier using the linear test equation that led the theory to a conclusion. The linear test equation is often called the Dahlquist equation .

In 1994 he received an honorary doctorate from the University of Helsinki , as well as an honorary doctorate from the Universities of Hamburg and Linköping .

In his honor, SIAM introduced the Dahlquist Prize in 1995 , which is awarded every two years to young scientists up to 45 years of age for scientific achievements in areas related to Dahlquist.

Fonts (selection)

  • A Special Stability Problem for Linear Multistep Methods. In: BIT Numerical Mathematics. Vol. 3, No. 1, 1963, pp. 27-43, doi : 10.1007 / BF01963532 .
  • On accuracy and unconditional stability of linear multistep methods for second order differential equations. In: BIT Numerical Mathematics. Vol. 18, No. 2, 1978, pp. 133-136, doi : 10.1007 / BF01931689 .
  • with Åke Björck: Numeriska metoder. Gleerup, Lund 1969, (In German: Numerical methods. Oldenbourg, Munich et al. 1972, ISBN 3-486-33851-X ).
  • with Åke Björck: Numerical methods in scientific computing. Volume 1. Society for Industrial and Applied Mathematics, Philadelphia PA 2008, ISBN 978-0-89871-644-3 .

Web links

Individual evidence

  1. ↑ Germund Dahlquist in the Mathematics Genealogy Project (English)Template: MathGenealogyProject / Maintenance / id used
personal data
SURNAME Dahlquist, Germund
BRIEF DESCRIPTION Swedish mathematician
DATE OF BIRTH January 16, 1925
PLACE OF BIRTH Uppsala , Sweden
DATE OF DEATH February 8, 2005
Place of death Stockholm