24 Numerics library [numerics]

24.8 Numeric arrays [numarray]

24.8.9 Class template indirect_­array [template.indirect.array]

24.8.9.3 Compound assignment [indirect.array.comp.assign]

void operator*= (const valarray<T>&) const; void operator/= (const valarray<T>&) const; void operator%= (const valarray<T>&) const; void operator+= (const valarray<T>&) const; void operator-= (const valarray<T>&) const; void operator^= (const valarray<T>&) const; void operator&= (const valarray<T>&) const; void operator|= (const valarray<T>&) const; void operator<<=(const valarray<T>&) const; void operator>>=(const valarray<T>&) const;
These compound assignments have reference semantics, applying the indicated operation to the elements of the argument array and selected elements of the valarray<T> object to which the indirect_­array object refers.
If the indirect_­array specifies an element in the valarray<T> object to which it refers more than once, the behavior is undefined.