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The **Seminar for Applied Mathematics (SAM)** at ETH Zurich and its precurser, **Institute for Applied Mathematics (IAM)**, have a remarkable history.

## SAM History

### The beginnings around 1948

The precurser of the Seminar for Applied Mathematics (SAM) (in German: Seminar für Angewandte Mathematik) at ETH Zurich, the Institute for Applied Mathematics (IAM) was founded on January 1, 1948, at the request of Professor **Eduard Stiefel** (21.4.1909-25.11.1978), who had been a full professor of mathematics since 1943, well known for his earlier contributions to pure mathematics. His vision was to introduce applied mathematics at ETH based on the usage of electronic computers as they were being developed in the United States, England, and the Netherlands. Among his early goals was the construction of a Swiss programmable electronic computer. As his first collaborators he hired two permanent assistants **Heinz Rutishauser** (30.1.1918-10.11.1970), a mathematician, and **Ambros P. Speiser** (13.11.1922-10.5.2003), an electrical engineer.

For gathering information on the current status of computer technology, Stiefel went in October 1948 for five months on a fact finding mission to Amsterdam and several places of the United States. He also sent his two assistants for a year to the two top U.S. computer research centers: Harvard and Princeton.

When Stiefel returned from the U.S., he learned that the Z4 computer, the fourth computer the ingenious German **Konrad Zuse** (22.6.1910-18.12.1995) had constructed during WWII had survived the war and was available for rent.

He decided to rent it for a period of five years. It was installed at ETH in August 1950. Thanks to the Z4, Stiefel and his collaborators could quickly start working on numerical methods and their applications. Today we would say that in 1950 they started to work in computational science, and they were very successful in that. Their fundamental contributions to numerical algorithms are legendary: in particular, Stiefel's conjugate gradient (CG) method (found independently also by Magnus Hestenes and Cornelius Lanczos at the Institute for Numerical Analysis attached to UCLA in Los Angeles, CA) and Rutishauser's quotient-difference (qd) algorithm and his LR algorithm, the predecessor of the ubiquitous QR algorithm of John G.F. Francis (England) and Vera N. Kublanovskaya (USSR).

Simultaneously, under the leadership of Ambros Speiser and Heinz Rutishauser, the staff of the IAM designed and constructed in the time range 1950-1956 a much faster electronic computer, the **ERMETH** (Elektronische Rechenmaschine der ETH), which was operational from 1956 until 1963. Moreover, during this period Heinz Rutishauser developed the concept of a compiler and was one of the main contributors to the groundbraking computer language ALGOL 60, and Hans-Rudolf Schwarz (*20.11.1930) wrote the first compiler for it.

Heinz Rutishauser became a Privatdozent in 1951, an associate professor in 1955, and a full professor in 1962. On November 10, 1970, he died at the age of 52.

Ambros P. Speiser became a Privatdozent in 1951, but in 1955 he left ETH to become the founding director of the IBM Research Laboratory in Rüschlikon near Zurich. When he left, Peter Läuchli (*4.6.1928) and Alfred Schai (21.4.1928-28.5.2009) were responsible for completing the ERMETH. Peter Läuchli became an assistant professor in 1964 and an associate professor in 1968.

### From the 60' to the 90'

In the wake of an offer from TH Munich, Heinz Rutishauser officially left the IAM in 1968 and founded, together with the newly promoted associate professor Peter Läuchli and the newly hired full professor Niklaus Wirth (*15.2.1934) the Fachgruppe Computer Wissenschaften, which was upgraded into the Institut für Informatik in 1974. Also in the 1960s, Eduard Stiefel gradually changed his research interest from numerical analysis to celestial mechanics, an area of wide interest at the great time of space flights. End of 1969, the Institut für Angewandte Mathematik was renamed Seminar für Angewandte Mathematik because Eduard Stiefel and **Peter K. Henrici** (13.9.1923-13.3.1987) decided to join forces. Peter Henrici had been a full professor of mathematics at ETH since 1962, and he was already a famous numerical analyst. But the rules for an institute did not allow that it was lead by two full professors who were on a par, while the rules for a seminar assumed that it had an acting director who is just primus inter pares.

In spring 1970 the two groups joined and moved to the newly erected RZ building at Clausiusstrasse 55. Moreover, in December 1970, Jürg T. Marti (*24.5.1935) came to the SAM as an associate professor; in 1976 he was promoted to full professor.

From 1974 to 1977 **Rudolf E. Kálmán** (*19.5.1930), the pioneer of modern systems and control theory, was also a full professor at the SAM. (Later he held an independent professorship at the Department of Mathematics.) The research of the other professors focused on the application of group theory (Stiefel), on applied and computational complex analysis (Henrici), and on approximation theory as well as computational fluid dynamics (Marti).

On November 25, 1978, **Eduard Stiefel** died at age 69 still in office. He was later formally replaced by **Jürgen Moser **(4.7.1928- 17.12.1999), who did not join the SAM, however, and had little interest in numerical mathematics. Another blow to the institute was the death of **Peter Henrici **on March 13, 1987, at the age of only 63. Unfortunately, in the 1980s, replacing first Stiefel and then also

Henrici at the SAM was repeatedly delayed by the Department of Mathematics. Thus the mid 1980s saw the nadir of the SAM with **Jürg Marti **the only remaining faculty. Nevertheless, the SAM kept its heavy teaching duties due to the commitment of its staff lectureres, notably, **Jörg Waldvogel, Urs Kirchgraber, Martin Gutknecht** and **Kaspar Nipp**.

Tides changed with the arrival of **Rolf Jeltsch** (*31.10.1945) in 1989 from RWTH Aachen and of **Randall J. LeVeque** (*30.9.1955) in 1990 from the University of Washington in Seattle. Both were experts in numerical methods for multi-dimensional hyperbolic conservation laws (shallow water equations, gas dynamics, magneto-hydrodynamics) and brought this new subject to the SAM, and along with it, fresh

momentum for research. However, for family reasons LeVeque chose to return to the U.S. in 1991. Again, it took four years and Rolf Jeltsch's unrelenting efforts until the vacancy was filled by **Christoph Schwab** (*14.10.1962, assoc. professor in 1995, full professor in 1998), who greatly invigorated SAM research in the field of numerical methods for elliptic boundary element methods, in particular,

finite elements and boundary elements.

### Today

At the turn of the century **Jürg Marti **retired and two years later in autumn 2002 **Ralf Hiptmair** (*10.5.1967, assoc. professor in 2002, full professor in 2005) was appointed as his successor. His research is focused on computational electromagnetism and wave propagation, with close links to industrial applications.

At that time **Christoph Schwab** broadened his research to include high-dimensional problems and uncertainty quantification. In 2007 the SAM moved into the spotlight when the institute was in charge of organizing the major International Conference on Industrial and Applied Mathematics (ICIAM).

When Rolf Jeltsch retired in 2011, **Siddhartha Mishra **(*5.5.1980, assoc. professor in 2012, full professor in 2015), assistant professor at the time, was chosen as his successor. He is a leading researcher in the theory and numerical methods for conservation laws, also encompassing uncertainty quantification and applications from computational biology. He and **Christoph Schwab** successfully applied for big research grants from the European Research Council (ERC).

Successfully finishing a campaign already initiated in 2008, in 2013 the SAM was allowed to advertise another faculty position from funds released by retirements. It was filled in summer 2015 with **Habib Ammari** (*28.06.1969, full professor from the beginning) a world expert in wave propagation, imaging and inverse problems. Thus, as of the beginning of 2016, the institute comprises four full

professors, two assistant professors, and two senior scientists, plus many more postdocs and doctoral students.

It is appropriate to emphasize the important contributions made by senior scientists throughout the history of SAM. The longest serving of them is **Jörg Waldvogel **(*24.2.1938, SAM staff as of 1972, Titularprofessor as of 1985, retired 2003), who over many years taught numerical methods to generations of undergraduate students and provided invaluable consulting services for scientists at ETH and in industry. His main research interests have been in celestial mechanics and computer supported number theory.

**Martin Gutknecht** (*1.10.1944, SAM staff from 1977 until 1988 and again as of 1999, Privatdozent 1980, Titularprofessor as of 1996, retired 2009), left SAM in summer 1988 to become the founding director of the Interdisciplinary Project Center for Supercomputing (IPS). At the beginning of 1996 the IPS got integrated into the Swiss National Supercomputing Center (CSCS) in Manno, Ticino, where from 1996 till 1998 Martin Gutknecht was the Scientific Director and leader of a sizable group of computational scientists. After the reorganization of CSCS Martin Gutknecht returned to SAM in 1999. In earlier times he had been working in approximation theory and computational complex analysis; meanwhile he has concentrated on the field of numerical linear algebra.

**Kaspar Nipp** (*5.3.1949, SAM staff as of 1983, Titularprofessor as of 2003, retired 2014). As a teacher he introduced many engineering students at ETH Zurich to linear algebra, and as an administrator he took care of every aspect of the ETH's pioneering study programs in Computational Science and Engineering (RW/CSE). His research interests have been ordinary differential equations and dynamical systems, in particular singular perturbations, invariant manifolds and their application in numerical analysis.

A special arrangement also brought **Rene Sperb** (*7.5.1943, at ETH as of 1978, at SAM as of 2003, Privatdozent 1980, Titularprofessor as of 1994, retired 2008) into the folds of SAM. He was a consummate teacher of mathematics to students of all sciences. His main interests have been mathematical modeling and reaction diffusion problems.

**Wesley Petersen** (*20.9.1945, SAM staff as of 1999, Titularprofessor as of 2006, retired 2010) was hired in 1988 for the IPS as a top expert in supercomputing, but he also brought expertise in parallel computing and the freshly evolving field of randomized algorithms.

No less important is the role of the current senior scientists at SAM, **Vasile Gradinaru** (as of 2011), Advisor of Studies

CSE, and **Roger Käppeli** (as of 2016), expert of high-performance computing.

Moreover, since 1991 a number of assistant professors, who officially held independent positions in D-MATH, had close links to the SAM: **Christian Lubich** (at SAM 08/1991-08/1992), **Martin Buhmann** (at SAM 04/1994-03/1997), **Marcus Grote** (at SAM 10/1997-03/2001), **Andreas Prohl** (at SAM 04/2002-04/2006). From April 2007 through August 2010 **Manuel Torrilhon** joined the SAM as an assistant professor funded by an EURYI grant. In 2008 the SAM seized the opportunity offered by the retirement of permanent senior scientists to create two assistant professors positions within the institute. Those were filled with **Daniel Kressner** (at SAM 09/2008-04/2011),** Siddhartha Mishra** (at SAM 08/2009-07/2011), **Philipp Grohs** (at SAM from 10/2011), and **Arnulf Jentzen** (at SAM from 09/2012). All these gifted young mathematicians brought their expertise and enthusiasm to SAM, most quickly built their own groups and contributed to an atmosphere of enterprising research spirit at the SAM. It goes without saying that all former assistant professors mentioned above received offers for tenured faculty positions at top universities long before their contracts at ETH would have expired.

In the late 90s the SAM took the lead in establishing an interdisciplinary study program in Computational Science and Engineering (RW/CSE at ETH Zurich, one of the first of its kind worldwide and still thriving today. The initiative to establish a CSE program at ETH Zurich came from **Rolf Jeltsch**, **Martin Gutknecht** (CSCS) and **Walter Gander** (Computer Science). To prepare a concept for the new curriculum, in December 1995 the ETH Zurich Executive Board appointed a committee consisting of **Walter Gander**, **Martin Gutknecht, Rolf Jeltsch, Kaspar Nipp** and **Wilfred van Gunsteren** (Chemistry). In 1997 the curriculum started as a diploma program (third and fourth year of studies). In 2003 it became a Bachelor/Master program starting in the second year of studies, and finally as of 2008 the CSE Bachelor curriculum became a full program starting in the first year of studies. From the beginning, the SAM faculty has been heavily involved in administration, curriculum design and teaching for ETH's CSE program.

### Literature

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