Local Convexity-Preserving 𝐶² Rational Cubic Spline for Convex Data

Figure 2

Comparison of convexity- and nonconvexity-preserving curves.

(a) Cubic Hermite curve

(b) PCHIP curve

(c) 𝐶² convex rational cubic curve with 𝑢_𝑖=0.25, 𝑣_𝑖=0.25

(d) 𝐶² convex rational cubic curve with 𝑢_𝑖=1.75, 𝑣_𝑖=1.75