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The Computing Girls of Van Wijngaarden

The Unsung Heroes:

Eddy Alleda, Dineke Botterweg, Ria Debets,
Marijke de Jong, Bertha Haanappel, Emmy Hagenaar,
Truus Hurts, Loes Kaarsenmaker, Corrie Langereis,
Reina Mulder, Diny Postema and Trees Scheffer

When the Second World War ended in 1945, the Dutch were determined to rebuild the ruins that the previous years had left them with. Since the Dutch government believed that Mathematics could play a vital role in this reconstruction, they hired mathematician Aad van Wijngaarden to set up the ‘Mathematical Centre’. Here, commissioned by the government, a team of mathematicians would perform calculations for, among others, the nautical and aviation industries.

A major part of this team of mathematicians was a group of 12 women that would perform calculations by hand. Most of them came directly from high school, having been selected on their excellent performance during those years. At the Mathematical Centre, they would function as ‘human computers’, taking up complicated calculations requiring them to differentiate, integrate and iterate; digit by digit, they would compute entire table books. As computer pioneer Jaap Zonneveld would remark years later: “they were not only named the computers, they were the computers”.

In 1954, for which Aad had made several educational trips to the United Kingdom and the United States, the first - successful - electromechanicalcomputerwascreatedonDutch soil. This computer, the ARRA II (Automatische Relais Rekenmachine Amsterdam), would take over the arduous calculatory tasks that had previously been done by the group of women. Nevertheless, its introduction did not make those women any less indispensable. Rather, it rendered them deft programmers: they would no longer do calculations by hand, but they would write programs for the computer to do it for them. As programmers, the women contributed to memorable achievements, such as the engineering of the Fokker F27, which would become one of the most successful passenger airplanes in history.

According to historian Gerard Alberts, Aad and his ‘computing girls’ marked the start of Dutch Computer Science. Not only did they play a crucial role in the advancement of the hardware industry, but they equally created the programming languages Algol 60 and Algol 68. Some of the concepts introduced in these languages are still used today.
Some of the Computing Girls at a reunion in 1986. From left to right: Truus Hurts, Dineke Botterweg, Bertha Haanappel, Eddy Alleda

On a less serious note, the Mathematical Centre also seemed to engender an atmosphere of fun. The women were known for laughing and chatting throughout the mathematical work, joining in on parties and vacations. Moreover, Aad showed a great attachment towards his girls, making sure they were taken care of in every possible way. As a matter of fact, the centre even saw the emergence of love and romance. Ria Debets, for example, married famous computer scientist Edsger Dijksta in 1957, who had previously provided the girls with a necessary crash course into programming.

The Computing Girls of Van Wijngaarden


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