RBF Definitions
“. . . Well, they are spherical triangles and there is a concave little and a concave big as viewed from inside and a convex little and a convex big as viewed from outside. Convex and concave are not the same; so there are inherently four. Infact, you will always find there are four there. Four is the minimum and when we get to any kind of system there is always four there. You will get used to the fourness. . . .”
