func I0(x float64) float64 { return float64(C.gsl_sf_bessel_I0(C.double(x))) }
// Zeroth-order modified Bessel function of the first kind (I0) func ModifiedBesselFirstKindZeroth(x float64) float64 { return float64(C.gsl_sf_bessel_I0(C.double(x))) }