Inverse of Error Function

I browsed the GSL hoping to find the Inverse of the Error Function .... unsuccessfully. While the Err function (Cumulative Density Function for the Gaussian distribution) is very easy to find in any scientific library... the Inverse of it, not analytically known, is hardly implemented. I'm looking for (hopefully) a free algorithm that implements the Inverse Error Function better if in C or C++, but also Fortran is fine. I'm not looking for tabulated values. Thank you in advance for any help. Maura E.M.