If is analytic on a domain , then a point on the boundary is called regular if extends to be an analytic function on an open set containing and also the point (Krantz 1999, p. 119).
Regular Point
See also
Ordinary PointExplore with Wolfram|Alpha
References
Krantz, S. G. Handbook of Complex Variables. Boston, MA: Birkhäuser, p. 119, 1999.Referenced on Wolfram|Alpha
Regular PointCite this as:
Weisstein, Eric W. "Regular Point." From MathWorld--A Wolfram Web Resource. https://mathworld.wolfram.com/RegularPoint.html