# smallgamma(n,x) is incomplete small gamma integral from 0 to x;

smallgamma(s_,a_,b_):=Gamma(s,a)-Gamma(s,b);
smallgamma(s_,a_,a_) :=0;
smallgamma(s_,0,b_):=Gamma(s)-Gamma(s,b);
smallgamma(s_,0,inf) := Gamma(s);
smallgamma(n_,x_):=Gamma(n)-Gamma(n,x);
smallgamma(n_):=Gamma(n);