"What Hadamard Missed"

Beresford Parlett (UC Berkeley)

In 1892 J. Hadamard received his doctorat d'etat degree for showing how to calculate the poles of a meromorphic function from its sequence of Taylor coeffcients. This problem has various applications but Hadamard's solution is no good for modern computation. We trace the gradual transformation of his formulae into a powerful robust algorithm. The contributions of Aitken (in the 1920's) and Rutishauser (in the 1950's) will be explained and the talk will end with recent modern developments.