**Germund Dahlquist** was a Swedish mathematician who worked in the theory of numerical analysis as applied to differential equations.

- Dahlquist entered Stockholm University in 1942 to begin his study of mathematics.
- These are qualities that Dahlquist shared to a high degree.
- Bohr took the time to discuss mathematics with his young student and inspired Dahlquist's early interests, which centred on analytic number theory, complex analysis, and analytical mechanics.
- Dahlquist would later refer to the profound influence on his view of mathematics of that early time with Bohr.
- Dahlquist received a first degree from Stockholm University in 1949 having written a thesis On the Analytic Continuation of Eulerian Products which he published in 1952.
- BESK came into operation in December 1953 and Dahlquist used the machine to solve differential equations.
- During this time Dahlquist wrote a number of papers such as The Monte Carlo-method (1954), Convergence and stability for a hyperbolic difference equation with analytic initial-values (1954), and Convergence and stability in the numerical integration of ordinary differential equations (1956).
- Dahlquist was now in a position to derive more realistic error bounds for problems that might not even be well-posed in reverse time.
- Dahlquist was to use this idea throughout his research in stiff differential equations.
- From 1956 to 1959 Dahlquist had been head of Mathematical Analysis and Programming Development at the Swedish Board of Computer Machinery.
- In the following year Dahlquist became Sweden's first professorship in Numerical Analysis when he became the professorial head of the Department which at this stage had six members of the academic staff.
- It was published in BIT, a journal which Dahlquist had played a major role in founding in 1961.
- The book Numerical Methods in Scientific Computing, Volume 1 by Germund Dahlquist and Ake Björck was published in September 2008.
- Tragically, my mentor, friend, and coauthor Germund Dahlquist died on February 8, 2005, before this first volume was finished.
- In 1990 Dahlquist retired from the Royal Institute of Technology in Stockholm, but remained very active in research.
- Dahlquist wrote to Marchuk pleading the dissident's case.
- After a long time with no response, two staff members of the Soviet Embassy called at Germund's office one day, bringing greetings from Marchuk and a package, that turned out to contain ...
- On one visit to the USA, with a few colleagues in a fine restaurant, Germund heard a female bar pianist whose music was obviously the highlight of the evening for him.
- When it was time to leave, Germund told the pianist how much he had enjoyed her stylish playing, adding that it had reminded him of one of his favourites, the great jazz pianist Art Tatum.
- He succeeded, in an extraordinary way, to relate stability concepts to accuracy and proved the deep results which are nowadays called the first and second Dahlquist barrier.

Born 16 January 1925, Uppsala, Sweden. Died 8 February 2005, Stockholm, Sweden.

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Origin Sweden

**O’Connor, John J; Robertson, Edmund F**: MacTutor History of Mathematics Archive