The following formulas give natural differintegral (that is one with naturally fixed integration constant):
$$f^{(s)}(x)=\sum_{m=0}^{\infty} \binom {s}m \sum_{k=0}^m\binom mk(-1)^{m-k}f^{(k)}(x)$$
$$f^{(s)}(x)=\frac{1}{2\pi}\int_{-\infty}^{+\infty} e^{- i \omega x}(-i \omega)^s \int_{-\infty}^{+\infty}f(t)e^{i\omega t}dt \, d\omega = \mathcal{F}^{-1}\left((-ix)^s \mathcal{F}(f(x))\right)$$
When $s=-1$ the expressions produce the antiderivative of the function $f(x)$. I wonder, whether there are any practical applications where the integration constant fixed this way is useful? For instance, unsurprisingly it gives $\sin(x+\frac{\pi s}2)$ as differintegral of sine, but non-trivially gives $\ln(x)+\gamma=\ln(xe^{\gamma})$ as integral of $1/x$
I also wonder whether $\ln(xe^{\gamma})$ has any intuitive meaning (especially given the analogy between $e^{-\gamma}$ and $\frac{\pi}4$).
