The fractional derivative of f(t) of order μ>0 (if it exists) can be defined in terms of the fractional integral D^(-ν) f(t) as D^μ f(t) = D^m[D^(-(m - μ)) f(t)], where m is an integer >=⌈μ⌉, where ⌈x⌉ is the ceiling function. The semiderivative corresponds to μ = 1/2.
