A model for a Kernel using
Cartesian
coordinates to represent the
geometric objects. In order for Simple_cartesian<FieldNumberType> to model Euclidean geometry
in $$E^{2} and/or $$E^{3}, for some mathematical field $$E (e.g.,
the rationals or the reals ), the template parameter FieldNumberType
must model the mathematical field $$E. That is, the field operations on this
number type must compute the mathematically correct results. If the number
type provided as a model for FieldNumberType is only an approximation of a
field (such as the built-in type double), then the geometry provided by
the kernel is only an approximation of Euclidean geometry.