Template:cpp/numeric/valarray/notes ret

The function can be implemented with the return type different from std::valarray. In this case, the replacement type has the following properties:

• All const member functions of std::valarray are provided.
• std::valarray, std::slice_array, std::gslice_array, std::mask_array and std::indirect_array can be constructed from the replacement type.
• For every function taking a conststd::valarray<T>&except begin() and end()(since C++11), identical functions taking the replacement types shall be added;
• For every function taking two conststd::valarray<T>& arguments, identical functions taking every combination of conststd::valarray<T>& and replacement types shall be added.
• The return type does not add more than two levels of template nesting over the most deeply-nested argument type.