vector_slice<VectorType> project(viennacl::vector_range<VectorType> & vec, viennacl::slice const & s1) { assert(s1.size() <= vec.size() && bool("Size of slice larger than vector proxy!")); return vector_slice<VectorType>(vec, viennacl::range(vec.start() + s1.start(), s1.stride(), s1.size())); }