For the 7th derivative question, Dan, I think you want D[ (u^2+1)/(v^2+1), {x,7}, NonConstants->{u,v} ]. The documentation seems pretty good here to me; http://reference.wolfram.com/language/tutorial/Differentiation.html covers both higher-order derivatives and symbols that depend on x in its first few examples. I don't know of a way to have Mma give you an nth derivative for unspecified n, though. --Michael On Sun, Dec 7, 2014 at 7:58 PM, Allan Wechsler <acwacw@gmail.com> wrote:
That reminds me ... wasn't Stephen Wolfram on math-fun for a while way back in the day? Is this a false memory?
On Sun, Dec 7, 2014 at 7:23 PM, Dan Asimov <dasimov@earthlink.net> wrote:
Assume u(x) and v(x) are arbitrary infinitely differentiable functions R -> R.
Suppose I want to find the 7th derivative f^(7)(x) of
f(x) := (u(x)^2 + 1) / (v(x)^2 + 1)
Is there a straightforward (or otherwise) way to do this in Mma???
Even better, can it give a general formula for the nth derivative in terms of n ???
(The online Mma documentation is pretty good -- much better than what you get with a ?? command while running the program -- but it doesn't make finding the answer to such questions easy.)
Thanks,
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