Researcher Ben Sommeijer of the Centrum Wiskunde & Informatica (CWI), the national research centre for mathematics and computer science in Amsterdam, the Netherlands, passed away on November 19, 2009. He has been working at the Mathematisch Centrum (now called CWI) since 1976 in the field of numerical mathematics, in particular the numerical integration of ordinary and partial differential equations. Ben Sommeijer has become sixty years.
Ben Sommeijer studied mathematics and scientific computing at the Eindhoven University of Technology and the University of Amsterdam (UvA) in 1967-1977. He began at the Mathematisch Centrum - the predecessor of CWI - as a scientific programmer in 1976. In 1988 he became researcher, and four years later he received his PhD degree at the UvA, with Piet van der Houwen as his supervisor.
Characteristic for his research was a high level of practicality, but with a precise and thorough basis. For example, he developed the Runge-Kutta-Chebyschev methods - first in collaboration with Piet van der Houwen and later with Jan Verwer. He has also contributed to a very successful applied study of the dynamics of phytoplankton, in collaboration with Jef Huisman (UVA) and Nga Pham Thi (PhD, CWI). This research has yielded an article in Nature.
Ben Sommeijer was chairman of the works council from 2001 to 2005. Furthermore he was for many years editor of the Journal of Computational and Applied Mathematics, and he co-organized the NUMDIFF conference that takes place every three years in Halle (Germany). This work included editing the conference proceedings for the Applied Numerical Mathematics journal.
We will remember Ben Sommeijer as an excellent colleague and researcher, and as a friendly and interested person.
