newbie: function of function of function ...

[Dot Deb]

Maybe the subject can be misleading but expresses well my confusion.
It is my n-th attempt with octave and every time I try I I get stuck
with some "stupid" problem.
This time I decided to go on and ask for help.

I think the problem is trivial but I just don't see the solution.

I need a funcioin that computes the integral (using something like
quadgk or quadcc) from -Inf to +Inf of an integrand like this:

f(x) * log( f(x) )

where f is the argument of the function

Naively, should read as:

function retval = entropy( f )
  quadcc( f*log(f), -Inf, +Inf)
end

I know that, if I define a somewhere function, say "gauss", I can write

f = @(x) -gauss(x) .* log( gauss(x) );
quadcc(f,-Inf,+Inf)

and it gives the right result.

The problem is that I need to include the two lines above in a
function that uses another function name as argument.
And I couldn't sort it out :(

Alberto