[GiNaC-list] using an "undefined" function

[Jose Antonio Garcia Peiro]

Hi,

I try to use an undefined function, such as f(x), instead of
f(x)=3*x+... I know that the function depends on variable x, but not
in what form.
With SymbolicC++, if I define Symbolic x("x"), f[x] and g[x], the
operation diff( f+g ,x ) returns diff(f,x)+diff(g,x). (the
differentiation rule of sum operator)
It is possible to make this with GiNaC?

Thanks