diff() function

[DrD]

(11-09-2014 02:29 PM)DrD Wrote:  6.) diff(diff(f(x,y),y)) ---> -2
7.) diff(-2*x+6*y-2,y) ---> 6
8.) diff(f(x,y),y$2) ---> 6

Modifying step (6.) thus: diff(f(x,y),y,y) works. In step (8.) (given by the y$2), y is sufficiently specified as the variable to use for each following derivative?

-[or]-

In the case: ∂(diff(f(x,hpdiffx),hpdiffx),y) ---> 6 The variable of differentiation is specified only once.

That's a lot to remember. The user guide description for the diff() topic could be expanded for more clarity. I think that about wraps up my interest in this function. Thanks Han, for taking all the time explaining details!

-Dale-