Only a default constructor is required. Note that further constructors can be provided.
 
A default constructor.


 
Returns an object, which has to be able to compute the squared radius of the circle of the points p0, p1, p2 or the squared radius of smallest circle of the points p0, p1, as FT associated with the metric used by Dt. 

 
Returns an object, which has to be able to compute the relative position of point test to the smallest circle of the points p0, p1, using the same metric as Dt. 