# erfi(x) is the imaginary error function ;
# erfi(x_):= If(x==0, 0, If(x==inf, inf, If(iscomplex(x) and re(x)==0, i*erf(im(x)), If(isnumber(x), nint(exp(t^2),t,0,x)*1.12838) )));
# erfi(n,x) is the nth derivative of the imaginary error function;

erfi(i*x_):= i*erf(x);
erfi(0):=0;
erfi(inf):=inf;