fancysuksa lujvo

function f1 is discontinuous/abrupt/sharply changes locally (in output) on/at s2 (set), with abruptness of type x3 (default: 1)

s2 should be a set within some open subset of definition of f1, or a set on which f1 is not defined at all. For x3, an argument of n (number) corresponds to a differentiability class of order n, to which f1 does NOT belong at points in set s2; notice that such an n makes no implications about the truth value of f1 belonging to any given differentiability classes of order m1 cannot belong to differentiability classes of order m>n; n=0 implies that the function is not continuous on that set (lack of definition there is sufficient for such a claim); a function that is discontinuous or which has a cusp or sharp 'corner' in its graph/plot (meaning that its derivative is discontinuous) at points in s2 will have n≤1. For now at least, n can be a non-negative integer; generalizations may eventually be defined. This lujvo is not perfectly algorithmic/predictable.