Very basic partial derivatives problem

[mnb96]

Hello,
I should feel ashamed to ask this, but it's giving me (and others) some troubles.

given f(x_1,\ldots,x_n), is it wrong to say that:

\frac{\partial f}{\partial f}=1

...?

 

[CompuChip]

It doesn't make a lot of sense... the idea is that in the expression \frac{\partial f}{\partial x}, f is a function and x is a variable on which f does (or does not, or does indirectly) depend.

You can write
\frac{\delta f(x_1, \cdots, x_n)}{\delta f(x_1', \cdots, x_n')} = \delta(x_1 - x_1') \cdots \delta(x_n - x_n')
where the delta's on the right hand side are Dirac delta distributions, but you are taking functional derivatives then.

 

[mnb96]

uhm...it makes some sense in the following context:
https://www.physicsforums.com/showthread.php?t=365940
however, there must be a mistake but I cannot see it.

[EDIT]: in the thread mentioned above a solution to the problem is described in its correct context. Sorry for this kind of "double posting"; in the beginning I thought I was facing a different problem than the original.