Openspecfun provides amos and faddeeva.

amos (from netlib) is a portable package for bessel functions of a complex argument and nonnegative order; it contains subroutines for computing bessel functions and airy functions.

faddeeva allows computing the various error functions of arbitrary complex arguments (faddeeva function, error function, complementary error function, scaled complementary error function, imaginary error function, and dawson function); given these, one can also easily compute voigt functions, fresnel integrals, and similar related functions as well.

this package contains a shared version of the library.