First of all, f(x)=x! where x is integer- is a group of dots on the plot. If you want to derivate such function like f(x)=x!, you should do it in complex numbers with Gamma function Г(z+1)=z! where Re(z)>0. Check it out on Wikipedia, it is interesting.

First of all, f(x)=x! where x is integer- is a group of dots on the plot. If you want to derivate such function like f(x)=x!, you should do it in complex numbers with Gamma function Г(z+1)=z! where Re(z)>0. Check it out on Wikipedia, it is interesting.