Interpolation by Convex Quadratic Splines

David F. McAllister, John A. Roulier
1978 Mathematics of Computation  
Algorithms are presented for computing a quadratic spline interpolant with variable knots which preserves the monotonicity and convexity of the data. It is also shown that such a spline may not exist for fixed knots.
doi:10.2307/2006342 fatcat:ds564gr5prh63l7u2ku4klq2ii