Hi,Hagan and West have published very great papers on the concept and implementation of monotone convex.www.math.ku.dk/~rolf/HaganWest.pdfThe pseudocode posted in the appendix suffices to implement the monotone convex interpolation.However, I am still not grasping the intuition behind the 4 quadrant Figure 4. I get it that we are dealing with:g(0) and g(1) in their various -ve and +ve combinations.But what about the lines g'(0)=0 (Line A) and g'(1)=0 (Line B) cutting through the quadrant, forming 4 different regions?Does it mean, to the right of the line A, the gradient is negative, and to the left of line A, the gradient is positive?And it is conversely true for line B?And why is it so?Appreciate any advices on this point.Thanks.

Ok, got the intermediate answer. Line A describes a set of points (G0, G1) whose gradients are 0 at G0. It follows that Line B describes a set of points (G0, G1) whose gradients are 0 at G1. What exactly are the adjustments made to Region 2,3,4?