三次样条插值，来自于数值分析方法一书

C Abstract: interpolate cubic spline profiles to given points.

C cubic splines are piecewise cubic polynomials fitting the data

C with continuous first and second derivatives at interior points

C and second derivatives set to zero at and beyond the end points.-Cubic Spline Interpolation

C Abstract: interpolate cubic spline profiles to given points.

C　 cubic splines are piecewise cubic polynomials fitting the data

C　 with continuous first and second derivatives at interior points

C　 and second derivatives set to zero at and beyond the end points.