Function pstore_partial

include/Eigen/src/Core/GenericPacketMath.h:899–907

 * offset + n <= unpacket_traits::size */
template <typename Scalar, typename Packet>
EIGEN_DEVICE_FUNC inline void pstore_partial(Scalar* to, const Packet& from, const Index n, const Index offset = 0) {
  const Index packet_size = unpacket_traits<Packet>::size;
  eigen_assert(n + offset <= packet_size && "number of elements plus offset will write past end of packet");
  EIGEN_ALIGN_MAX Scalar elements[packet_size];
  pstore<Scalar>(elements, from);
  for (Index i = 0; i < numext::mini(n, packet_size - offset); i++) {
    to[i] = elements[i + offset];
  }
}

/** \internal copy the packet \a from to \a *to, (un-aligned store) */
template <typename Scalar, typename Packet>