. . . I got my "repeated" procedure to work (Ex. 1.43). It's not an earth-shaker but, as my Scottish great-grandmother used to say, "A wee thing pleases the wane." But I'm still not sure what the notation "|->" is all about. What's the difference between saying "if f is the function x |-> x + 1" and "if f is the function f(x) = x + 1" ? Anyway, tomorrow on to smoothing (Ex. 1.44).