# exp(x) is exp function;
# exp(n,x) is the nth order derivative of exp(x);
#exp(a_,x_):=exp(x);

exp(log(x_)):=x;
exp(a_*log(x_)):=x^a;
exp(log(x_)*y_):=x^y;

exp(i*pi):= -1;
exp(-W(1)):=W(1);