Are there any fractional derivative calculators available in any Computer Algebra Systems or other Mathematical softwares?
I wish to find the value of $D^a\ln(1+e^x)$ for $x=0,a=0.9$. Is there a way to do it using manually or a suitable open source software? From this paper, page 7546, the value of the function above is defined as softplus activation function, and its fractional derivative is given as $$\lim\limits_{h\to0}\dfrac1{h^{a}}\sum_{n=0}^{\infty}(-1)^n\dfrac{\Gamma(a+1)\left(1+e^{x-nh}\right)}{\Gamma(n+1)\Gamma(1-n+a)}$$ I am unable to understand how to evaluate this limit at $x=0,a=0.9$. The paper linked has shown the plot of the function as different values of $a$, but it is unclear how or what software they used. Any hints? Thanks beforehand.