其基本思想是取B样条函数 为及基函数，在[a,b]中均匀划分区间，xi=a+ih,h=(b-a)/n,由于三次样条函数空间是n+3维的，所以把分点扩充到x-1,xn+1,则任意三次样条函数可用 线性组合来表示：-The basic idea is to take B-spline function and basis functions in [a, b] in the evenly divided intervals, xi = a+ ih, h = (ba)/n, because the cubic spline function is n+3 dimensional space , so the expansion points to the x-1, xn+1, then any cubic spline function can be expressed as a linear combination: