No Fit Boundary Analytic Equation and Interference Detection for Ellipse-ellipse
椭圆-椭圆不适合边界的解析方程及其干涉判断

In many computer visualized fields such as medical and surgical operations and virtual assembly,it is of ten neecessary to detect the interference between ellipses.The No Fit Boundary(NFB) of ellipse-ellipse is obtained according to the algebraic condition of exterior contact of ellipse-ellipse.To be specific,its generalized characteristic polynomial has positive double roots,which we proved further has only a double,root by using the affine transformation and inverse affine transformation.Itis easy to detect interference accurately between two ellipses using NFB analytic equation.The trajectory mapped by NFB can also detect the interfer ence quickly and visually.The above two methods can be used together in medicine.