cpp/numeric/valarray/begin2

The overload of std for returns an iterator of unspecified type referring to the first element in the numeric array.

@1@ The return type meets the requirements of mutable. @2@ The return type meets the requirements of constant.

The iterator obtained from this function is invalidated when the member function resize is called on the array or when the lifetime of  ends, whichever comes first.

Return value
Iterator to the first value in the numeric array.