Complex scaled complementary error function

Matlab provides the function erfcx which computes a scaled error function. However, the input argument must be real. This function computes the values of the Fadeeva function for complex inputs.

Note that W(i*x) = erfcx(x) for real-values x.

An error flag is set if the algorithm does not converge.

The algorithm is taken from the work published in TRANSACTIONS ON MATHEMATICAL SOFTWARE, VOL. 16, NO. 1, PP. 47.