In Memoriam – Emeritus Professor Marc Spijker
On 11 January 2026, our esteemed and much-loved former colleague, Prof. Dr Marc Spijker, passed away.
Marc was a brilliant scientist and an exceptional human being. He was born on 15 July 1939 in Leiden. In 1968 he obtained his doctorate from Leiden University, where at the young age of 31 he was appointed Professor of Numerical Mathematics in 1971. Marc worked at the Mathematical Institute, which from the early 1970s onwards was housed in the Snellius Building on Niels Bohrweg.
Marc’s research enjoyed great international recognition, and he was highly respected — both as a scientist and as a person — within the numerical mathematics community and beyond. He collaborated fruitfully with leading researchers in the Netherlands and abroad. Within the Netherlands, he maintained particularly close ties with colleagues at the Centrum Wiskunde & Informatica (CWI) in Amsterdam.
Marc made important contributions to the development of numerical mathematics in the Netherlands. Among other things, he was a co-founder in 1976 of the annual Woudschoten Conferences in Zeist, which bring together all numerical mathematicians from the Netherlands and Flanders. This year, the conference celebrates its 50th edition.
Marc’s field of research was the analysis of numerical methods for initial value problems for ordinary and partial differential equations. In numerical time integration, he studied both one-step methods (including Runge–Kutta methods) and general multistep methods. His research focused on the fundamental properties of these methods, such as stability, contractivity, monotonicity, boundedness and convergence. In doing so, he frequently drew on his extensive mastery of classical analysis, linear algebra and operator theory. He achieved numerous profound mathematical results, which he always formulated with great care and proved in an elegant and rigorous manner. His lectures and presentations were, without exception, crystal clear.
For his doctoral students — 17 in total — Marc was of inestimable value. He was an outstanding supervisor who always had time for them and who consistently supported, advised, encouraged and inspired them — calmly and thoughtfully — both academically and personally. There were many shared dinners with engaging conversations, as well as numerous enjoyable walks — in the surroundings of Leiden and in a wide range of other places around the world.
Marc retired in 2004. The farewell symposium held at the Mathematical Institute that year was attended by the majority of his former doctoral students. After his retirement, Marc remained active as a mathematical researcher for many years and continued to publish in leading journals in numerical mathematics.
As a person, Marc was warm, helpful and generous, with a genuine interest in others. He was principled and resilient, even in the most difficult moments of his life. He was always modest about himself. To many, however, he has been of great significance. He is deeply missed.
Text kindly provided by Karel In’t Hout and Hans Kraaijevanger.