That's a helpful link, thanks. At first glance it looks like, in all their examples, the control flow is oblivious to the values in the vectors. I suppose I'll

That's a helpful link, thanks. At first glance it looks like, in all their examples, the control flow is oblivious to the values in the vectors. I suppose I'll have to try it to see if/how it can differentiate factorial(x) with respect to x. ("You can't do that" would be a perfectly reasonable answer, but it's unclear to me if that's what it is.)