When Did the Concept of Residue in Complex Analysis Emerge?

[Giovanni]

Please anyone tell me about when, why and how did the concept of residue in complex analysis started?

 

[Tide]

Jean-le-Rond d'Alambert and Augustine Cauchy (and some others) made extensive studies of wave propagation along with fundamental mathematical discoveries relating to limits, continuity and covergence. Cauchy's integral theorem was one product of their investigations.