A point 
is a central point of a graph if the eccentricity of the point equals the graph
radius. The set of all central points is called the graph
center.
In analytic number theory, the central point of an L-function is the point fixed by the symmetry in its functional
equation. For a functional equation relating 
and 
, the central point is 
. For the classical normalization of an elliptic-curve
-function relating 
and 
, it is 
.
