[Help-gsl] Inverse error functions?

[Frank Chu]

Hi,

It seems like there are error functions in GSL (gsl_sf_erf, gsl_sf_erfc),
but their inverse do not exist.  Is this omission deliberate and there is an
easy way of computing the inverses that I'm missing?  Or are they not worth
it to add?
Would someone consider a change to add inverses to either or both of these
functions?  Boost's special functions library has them, for example.

Thanks,
Frank