29 Numerics library [numerics]

29.6 Numeric arrays [numarray]

29.6.8 Class template mask_array [template.mask.array]

29.6.8.4 Fill function [mask.array.fill]

void operator=(const T&) const;
This function has reference semantics, assigning the value of its argument to the elements of the valarray<T> object to which the mask_array object refers.