Input: XY(n,2) is the array of coordinates of n points x(i)=XY(i,1), y(i)=XY(i,2) Output: Par = [a b R] is the fitting circle: center (a,b) and radius R Note: this fit does not use built-in matrix functions (except "mean"), so it can be

采用拟三对角矩阵反算出过一定点（大于等于3个）的控制顶点，再由这些控制顶点计算出3次B样条曲线，由于曲线封闭的，所以无需引入边界条件即可求得曲线。-Used to be anti-tridiagonal matrix calculated over a certain point (greater than or equal to 3) of the control points and then calculate the control points of these 3 B-spline

目的：根据刚体变换理论计算rt矩阵，点云在旋转前后发生刚体变换，并不会对点云数据的模型进行改变 相对于最小二乘法的直接计算点云的方法，A=R*B,>> R=(A*B )*[inv(B*B )] 与该方法相比，该方法最直观， 但是会引起点云模型变形，该方法求出的rt，矩阵不是正交矩阵，而下面的方法则是刚体变换，不会引起点云数据 模型的变形-Objective: according to the theory of rigid body transformation ma