[Help-gsl] dawsons integral for imaginary arguments

[Carsten Fortmann]

I need the following expression

exp(x*x)erfc(x)  (1).

Due to the exp(x*x) (not exp(-x*x)!!!),
 this expression returns a  nan for large arguments. I found out, that 
(1) is in principal given by dawsons integral for purely imaginary 
argument. Does anyone know how to obtain this in gsl?

Carsten