Procedures for Natural Spline Interpolation [E1] (Algorithm A472) CACM December, 1973 Herriot, J. G. approximation, interpolation, spline, natural spline, spline approximation, cubic natural spline 5.13 CA731205 JB January 19, 1978 2:47 PM 2403 5 2403 2403 5 2403 2403 5 2403