inline static
typename std::enable_if<ExpansionTraits<Expansion>::has_vector_S2M>::type
apply(const Expansion& K,
SourceIter s_begin, SourceIter s_end, ChargeIter c_begin,
const typename Expansion::point_type& center,
typename Expansion::multipole_type& M) {
K.S2M(s_begin, s_end, c_begin, center, M);
}
inline static
typename std::enable_if<ExpansionTraits<Expansion>::has_scalar_S2M &
!ExpansionTraits<Expansion>::has_vector_S2M>::type
apply(const Expansion& K,
const typename Expansion::source_type& source,
const typename Expansion::charge_type& charge,
const typename Expansion::point_type& center,
typename Expansion::multipole_type& M) {
K.S2M(source, charge, center, M);
}
