Aurel Angelescu went to Paris for his university studies and graduated with a bachelor degree from the Sorbonne. On 7 April 1916 he was awarded (also from the Sorbonne) the degree of Ph.D. in Mathematics, after writing a thesis under the guidance of Paul Appell. The title of his thesis was Sur les polynômes généralisant les polynômes de Legendre et d'Hermite et sur le calcul approché des integrals multiples . In his book Fonctions hypergéométrique et hyperspheriques. Polynômes d'Hermite, published in 1926, Appell writes about the results in Angelescu's thesis. Appell also mentioned Angelescu's results on Hermite polynomials in his 1925 memoir Sur les fonctions hypergéométrique de plusiers variables, les polynômes d'Hermite et autres fonctions sphérique dans l'hyperespace .
After his return to Romania, following the recommendation of Gheorghe Țițeica, Aurel Angelescu was appointed, on 1 November 1919, as a professor at the Function Theory Chair of the University of Cluj. Now Cluj had, with the rest of Transylvania, been incorporated into Romania with the Treaty of Trianon in 1919. The University in Cluj, which had been named the Franz Joseph University since 1881, became a Romanian institution and was officially opened as such by King Ferdinand on 1 February 1920. Angelescu was fully dedicated to the intense work of organizing mathematical education at the University. Here, together with Nicolae Abramescu, Petre Sergescu and Gheorghe Bratu, he formed a strong and valuable kernel around Dimitrie Pompeiu, the Director of the Mathematical Seminar. Angelescu's position at Cluj was tenured in 1922. He became director of the Geometry and Mechanics Seminar and, for one year, between 1927 and 1928, he was appointed as Dean of the Faculty of Sciences at the University of Cluj. He was also one of the founders of the new journal Mathematica (Cluj) which began publishing in 1929. Beginning on 1 January 1930, Angelescu became full professor of Algebra and Number Theory at the University of Bucharest. There he succeeded Traian Lalescu. He held this position until his death in 1938.
Aurel Angelescu's main fields of interest were generating functions for polynomials, linear differential equations, functional analysis, trigonometric series and the general theory of algebraic equations. He was particularly interested in generating functions for Legendre, Laguerre and Hermite polynomials and one of his main research efforts was put into generalising these polynomials. He published more than 60 research works in the field of Algebra and Function Theory. Examples of his contributions are: Extrait sur les polynomes (1915); Sur le quardatures méchanique (1920); On the linear homogeneous recurrence relations with constant coefficients (Romanian) (1925); The definition of the functions of complex variable (Romanian) (1925); Sur certains développements des fonctions holomorphes en série de fractions rationnelles (1925); Sur une formule de M Pompeiu (1929); On some means (Romanian) (1932); Sur le principe de Legendre (1933); Sur une certaine extension des séries entières (1937); and Sur certains polynômes généralisant les polynômes de Laguerre (1938). The polynomials, generalising the Laguerre polynomials, which Angelescu defined in this 1938 paper are today known as the 'Angelescu polynomials'.
Angelescu played a large role in producing new lecture courses at the University of Cluj and he published many of these, some as single authored works and others along with his colleagues. His most important book was Lectures on Differential Calculus (Romanian) (1927). He also partly wrote and was the editor of Lectures on Mathematical Analysis: sets, limits, series, derivatives and differentials, extreme points, change of variables (Romanian) (1927). He published some of his lectures notes as Course of higher algebra (Romanian) (1931). He wrote many other books in Romanian, in collaboration with Dimitrie Pompeiu, Dumitru V Ionescu, Gheorghe Bratu and O Onicescu, such as Elementary Algebra, Arithmetic, and Geometry. These ran to many editions.
Angelescu was elected to the Romanian Academy of Sciences on 21 December 1935.
At the young age of almost 52 years, Professor Aurel Angelescu tragically died in April 1938. It appears that he took his own life but he did not leave anything to explain why he did this.
Article by: J J O'Connor and E F Robertson