ERFI _ _ _ _ _ _ _ _ _ _ _ _ operator
The erfi operator returns the error function of an imaginary argument.
erfi(~x) => 2/sqrt(pi) * defint(e**(t**2),t,0,x);
This operator is sometimes included in the result of the simplification of a generalized hypergeometric function or a MeijerG function.
No simplification is done for this function.