Preliminary Google's grant nothing, so I'll pose it here:
How may I go about solving equations for the independent when in the form $f(x) = x!$ ?
$x!$ being the factorial of $x$, i.e.: $4! = 4 \times 3 \times 2 \times 1$
I'm aware of factorial approximation methods such as Stirling's approximation; $x! \approx \sqrt{2 \pi x} \cdot \left(\dfrac{x}{e}\right)^x $; but am aware of no such method to solve for $x$ itself in the natural form.
Thoughts?