Erf function for large complex numbers

Hi, i'm looking for a function to evaluate the complex ref function for large complex number.

When i try using the internal matlab function (ref) or external e.g. http://it.mathworks.com/matlabcentral/fileexchange/18312-error-function-of-complex-numbers or http://it.mathworks.com/matlabcentral/fileexchange/38787-faddeeva-package--complex-error-functions

i found always the same problems.... for large complex numbers the result is NaN.

Can you help me? Thanks in advance

Andrea

[the cyclist]

How large is the argument? I'm guessing that if it is large enough, there will be some approximation to erf that is good enough.