I am a bit new in MAPLE and I was trying to write a function of $x$.
I define a function:
$W:=W_{d_{{\it ij}}}\,W_{f_{{\it ij}}}$
I would just like to write in MAPLE $diff(W,x)$ and get: $ \left( {\frac {\rm d}{{\rm d}x}}W_{d_{{\it ij}}} \left( x \right) \right) W_{f_{{\it ij}}} \left( x \right) +W_{d_{{\it ij}}} \left( x \right) {\frac {\rm d}{{\rm d}x}}W_{f_{{\it ij}}} \left( x \right) $
Instead I get just $0$ as a result. I know it is correct of MAPLE of giving me $0$ but how can I tell it that $W_D$ and $W_F$ are functions of $x$?
Thanks.
I found the error. It was pretty easy. I needed to add the dependency from $x$ (of course).
Basically to get what I wanted I needed to write the function as:
$W:=W_{d_{{\it ij}}} \left( x \right) W_{f_{{\it ij}}} \left( x \right) $
In this way I get the result:
$ \left( {\frac {\rm d}{{\rm d}x}}W_{d_{{\it ij}}} \left( x \right) \right) W_{f_{{\it ij}}} \left( x \right) +W_{d_{{\it ij}}} \left( x \right) {\frac {\rm d}{{\rm d}x}}W_{f_{{\it ij}}} \left( x \right) $
I hope it will help someone else.