根据曲线上的型值点，用追赶法求反算出3次B样条的曲线控制顶点，再由3次B样条的系数矩阵设定均匀节点（50份）矢量求出50个点。 左键输入，完后右键完成输入，重新绘制-Under the curve data points, with catch-up method to calculate the anti-3 B-spline curve control points, and then 3 times by B-spline c