#include <boost/qvm/quat_operations.hpp>
namespace boost
{
    namespace qvm
    {
        //Only enabled if: is_quat<A>::value
        template <class A>
        typename deduce_quat<A>::type
        normalized( A const & a );
    }
}
As if
typename deduce_quat<A>::type tmp; assign(tmp,a); normalize(tmp); return tmp;