Function gsl_sys::gsl_linalg_ldlt_band_unpack

pub unsafe extern "C" fn gsl_linalg_ldlt_band_unpack(
    LDLT: *const gsl_matrix, 
    L: *mut gsl_matrix, 
    D: *mut gsl_vector
) -> c_int

This is supported on crate feature v2_6 only.