03/11/2011, 10:59 PM

(03/11/2011, 10:07 PM)martin Wrote:(03/11/2011, 12:42 PM)bo198214 Wrote: For me it seems important that the curve t |-> a [t] b is smooth (or better analytic) for fixed a and b.

I mean you define it on the interval [1,2], i.e. between addition and multiplication, and then you would continue it to the higher operations t>2 by

a [t+1] (b+1) = a [t] ( a [t+1] b )

And then it would be interesting whether the curve is (infinitely) differentiable at t=2, t=3, etc. Of course it would between the endpoints, i.e. on (2,3) and (3,4), etc.

IIRC, this is exactly what I tried to do, some three years ago or so...

It never really worked out, though some sample graphs for 2 [4] x and 3 [4] x looked quite good.

Hey Martin, we are not talking about the function f(x) = a [4] x but about the function g(x) = a [x] b. But you are right that we expect the same smoothness also for f(x), which is how Andrew Robbins came to his tetration extension.