Van Wijngaarden at his desk, 1952.

Adriaan (Aad) van Wijgaarden (2 November 1916 - 7 February 1987[1]) studied mechanical engineering at the Delft University of Technology, graduating in 1939. He then studied for a doctorate in Hydrodynamics under supervision of Jan Burgers, but stopped during the second world war because the University was closed down. In December 1945 van Wijngaarden received his Ph.D. for calculations on ship propellers in the Applied Mechanics department under supervision of professor C.B. Biezeno.

Because of the war, new technologies didn't reach the European coast easily. From January until March 1946 van Wijngaarden traveled to London with a team of students picked by Burgers and Biezeno to gather knowledge of some new technology invented during the war[2]. This trip was reported to Biezeno. At first van Wijngaarden met A.C. Stevenson and W.M. Shephard, who became good friends of van Wijngaarden, and who showed him the mechanical calculation machines used during that period in England, for example the differential analyzer. In Manchester, van Wijngaarden met Hartree, who had constructed his own model of the differential analyser. There was a Meccano model of the differential analyzer available for presentations, but away from Manchester, this model was also used for calculations. Coming back in the Netherlands, Biezeno was impressed by the reports of van Wijngaarden.

Meanwhile he accepted a job at the National Aviation Lab (Nationaal Luchtvaartlaboratorium, NLL). He did not stay there for a long time though. In 1947 the just opened Mathematical Center offered him a job. Later on he tells that the reason to change his job was because he was offered freedom, even though the first offer came with a lower salary than his job at the NLL. Van Wijngaarden made trips to England and the United States for his job at the Mathematical Center, where he became the leader of the Computation Department. He stayed there until his retirement.

To construct the ARRA Van Wijngaarden used dumped relays.

During his trips to the United States and England Van Wijngaarden gathered ideas for the construction of the first Dutch computer, the ARRA. This was an electromechanical construction first demonstrated in 1952. One of the first things was searching for good researcher for his department. He contracted two students in Physics, Carel Scholten and Bram Loopstra for building a computer, the ARRA. Together they went to a place where old military stuff was dumped, to obtain Siemens high-speed relays. These components were used to construct the ARRA I. In 1952 Van Wijngaarden hired E.W. Dijkstra, and they worked on software for the machine.

Since Hartree was one of the most experienced men in building these early computers, Van Wijngaarden asked Hartree to visit his department. When asked how long it takes to finish building the machine, he consistently replied: "*around three months.*" This was called Hartree's Constant and actually means the machine's building process never ended[3]. Van Wijngaarden was very proud of his computing department and when somebody from the outside visited the department, he first let the visitor make contact with his researchers. Van Wijngaarden told the vistor that his computing department was unique in The Netherlands and the only department with the same level of research was the National Physical Laboratory in Teddington, UK.

The computing girls are considered heroes on their own. Read more about them.

In his new computing department at the Mathematical Center Van Wijngaarden also started contracting highly educated women, all of which excelled in mathematics. They were dubbed the computing girls of Van Wijngaarden ("de rekenmeisjes van Van Wijngaarden"). This was revolutionary in The Netherlands, since usually *mulo* (lower education) women helped at mathematical labs. Highly educated women making calculations at a mathematical department was something Van Wijngaarden saw for the first time during one of his trips to England. When one of the women wanted to quit and take some English courses, he even arranged an exchange trip to Teddington, UK, for two of the women[4], where he built up great connections. He also arranged trips because the working environment had to be good.

Another order from Fokker, a Dutch airplane manufacturer, was to build a machine to calculate the scope of the wings for a new plane, which would be the Fokker Friendship. This calculation machine was called FERTA. The Fokker Friendship was released in 1955 and the plane received the Dutch award for best design[5]. The FERTA had to be built very quickly and this was a reason to make up a bonus system. Everything had to be done by hand, so for every first paper with calculations a bonus fee of 1 cent was given, 2 cents for the second paper, et cetera.

Van Wijngaarden at a conference in 1954.

While visiting Edinburgh in 1958, Van Wijngaarden was severely injured in a car accident which killed his wife. After his recovery, he focussed more on the research of programming languages. This made him one of the designers of the original ALGOL. Van Wijngaarden became the leader of a group of scientists which designed its successor ALGOL 68. During the development of ALGOL 68 Van Wijngaarden developed a two-level type grammar that became famous as *Van Wijngaarden grammars*[6]. These grammars describe a manner to write infinite grammars in a finite number of lines. They were used to define syntactical constraints, which had to be defined in natural language until these grammars where invented. Example constraints are the uniqueness and definition of identifiers in a programming module. ALGOL 68 became a mathematical beauty which was hard to learn. Critics of ALGOL 68, prominently C. A. R. Hoare and E.W. Dijkstra, point out that it abandoned the simplicity of the earlier ALGOL 60 and became a vehicle for various complex ideas of its designers. It was also hard to write a compiler for the programming language, in contrast to deliberately simple competitors like C and Pascal. Examples of later developed programming languages influenced by ALGOL 68 are C++ and Ada.

Because of the advanced knowledge of Van Wijngaarden about computing methods, his work is characterized by mathematical beauty. Van Wijngaarden became the director of the Mathematical Center in 1961, and remained in that post for the next twenty years. In 2006 an award named after Van Wijngaarden was introduced marking the 60th anniversary of the Mathematical Center (now called the *Center for Mathematics and Computer Science* (CWI). The award is given to researchers with outstanding contributions to mathematics and computer science.

*Adriaan van Wijngaarden,*, 2007 .- "De geboorte van de Nederlandse informatica in Londen",
*Informatie*, 02/2006. - "Een halve eeuw computers in Nederland: 1. Een willekeurig getal",
*Nieuwe Wiskrant*, vol. 22, issue 1: Freudenthal Instituut, 10/2002. *Zij Mogen Uiteraard Daarbij De Zuivere Wiskunde Niet Verwaarloozen,*, Amsterdam, Centrum voor Wiskunde en Informatica (CWI), 1987 .- "Fokker Friendship",
*Delta*, vol. 38, issue 16, 05/2006. *Van Wijngaarden grammars,*, 2007 .