**Agner Erlang** was a Danish mathematician, statistician and engineer, who invented the fields of traffic engineering and queueing theory.

- Hans Nielsen arranged with one of his wife's relatives to let Agner live in their home in Hillerod for two years while he studied at the Frederiksborg Grammar School preparing to sit the university entrance examinations.
- Jensen persuaded Erlang to apply his skills to the solution of problems which arose from a study of waiting times for telephone calls.
- In 1908 Erlang joined the Copenhagen Telephone Company as a scientific collaborator and the head of their newly established physico-technical laboratory, and he began applying probability to various problems arising in the context of telephone calls.
- In the twenty years that Erlang worked for the Copenhagen Telephone Company he never had to take a day off through illness.
- Characteristic of Erlang's achievements within this field are his endeavours to deduce as much as possible from the single basic principle.
- In the case of these problems he found this basic principle in the assumption of the statistic equilibrium, a concept which was known, it is true, from other domains; it was Erlang's works, however, that disclosed the wealth of possibilities contained in this principle with regard to the theory of telephone traffic.
- The mathematically exact methods of solving problems of loss and waiting times, which Erlang developed by his employment of the principle of statistic equilibrium, are of fundamental importance in the theory of telephone traffic.
- In addition to his work on probability Erlang was also interested in mathematical tables.
- Erlang set forth a new principle for the calculation of certain forms of mathematical tables, especially tables of logarithms...
- Erlang was a beneficent man; living frugally, he could afford to help others, which he did to an even very great extent.
- At a meeting in Montreal in October 1946, Le comité consultatif international des communications téléphoniques à grande distance made the decision to name the International Unit of Telephone Traffic the "erlang".
- The quantity thus measured is of course dimensionless, and the erlang is to be compared with the octave, the stellar magnitude and the decibel in describing the mode of calculation rather than the unit of measurement in the usual sense of physics.
- Erlang has also been honoured by Ericsson Communications when it named the Erlang programming language after him.

Born 1 January 1878, Lonborg (near Tarm), Jutland, Denmark. Died 3 February 1929, Copenhagen, Denmark.

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Astronomy, Origin Denmark

**O’Connor, John J; Robertson, Edmund F**: MacTutor History of Mathematics Archive