 A function is "unimodal" if it is monotonically increasing up to some point (the "mode") and then monotonically decreasing.When formula_1 is a "strictly monotonic" function, then formula_1 is injective on its domain, and if formula_45 is the range of formula_1, then there is an inverse function on formula_45 for formula_1.In contrast, each constant function is monotonic, but not injective, and hence cannot have an inverse.