28 Numerics library [numerics]

28.6 Numeric arrays [numarray]

28.6.2 Class template valarray [template.valarray] Unary operators [valarray.unary]

valarray operator+() const; valarray operator-() const; valarray operator~() const; valarray<bool> operator!() const;
Mandates: The indicated operator can be applied to operands of type T and returns a value of type T (bool for operator!) or which may be unambiguously implicitly converted to type T (bool for operator!).
Returns: A valarray whose length is size().
Each element of the returned array is initialized with the result of applying the indicated operator to the corresponding element of the array.