Convergent expansions of the incomplete gamma functions in terms of elementary functions

We consider the incomplete gamma function γ(a,z) for Ra>0 and z∈C. We derive several convergent expansions of z−aγ(a,z) in terms of exponentials and rational functions of z that hold uniformly in z with Rz bounded from below. These expansions, multiplied by ez, are expansions of ezz−aγ(a,z) u...

Descripción completa

Detalles Bibliográficos
Autores: Bujanda Cirauqui, Blanca, López García, José Luis, Pagola Martínez, Pedro Jesús
Tipo de recurso: artículo
Estado:Versión aceptada para publicación
Fecha de publicación:2017
País:España
Institución:Universidad Pública de Navarra
Repositorio:Academica-e. Repositorio Institucional de la Universidad Pública de Navarra
OAI Identifier:oai:academica-e.unavarra.es:2454/31776
Acceso en línea:https://hdl.handle.net/2454/31776
Access Level:acceso abierto
Palabra clave:Incomplete gamma functions
Convergent expansions
Uniform expansions
Descripción
Sumario:We consider the incomplete gamma function γ(a,z) for Ra>0 and z∈C. We derive several convergent expansions of z−aγ(a,z) in terms of exponentials and rational functions of z that hold uniformly in z with Rz bounded from below. These expansions, multiplied by ez, are expansions of ezz−aγ(a,z) uniformly convergent in z with Rz bounded from above. The expansions are accompanied by realistic error bounds.