29 Numerics library [numerics]

29.8 Generalized numeric operations [numeric.ops]

29.8.5 Transform reduce [transform.reduce]

template <class InputIterator1, class InputIterator2, class T>
  T transform_reduce(InputIterator1 first1, InputIterator1 last1,
                     InputIterator2 first2,
                     T init);
template <class ExecutionPolicy,
          class ForwardIterator1, class ForwardIterator2, class T>
  T transform_reduce(ExecutionPolicy&& exec,
                     ForwardIterator1 first1, ForwardIterator1 last1,
                     ForwardIterator2 first2,
                     T init);

Effects: Equivalent to:

return transform_reduce(first1, last1, first2, init, plus<>(), multiplies<>());

template <class InputIterator1, class InputIterator2, class T,
          class BinaryOperation1, class BinaryOperation2>
  T transform_reduce(InputIterator1 first1, InputIterator1 last1,
                     InputIterator2 first2,
                     T init,
                     BinaryOperation1 binary_op1,
                     BinaryOperation2 binary_op2);
template <class ExecutionPolicy,
          class ForwardIterator1, class ForwardIterator2, class T,
          class BinaryOperation1, class BinaryOperation2>
  T transform_reduce(ExecutionPolicy&& exec,
                     ForwardIterator1 first1, ForwardIterator1 last1,
                     ForwardIterator2 first2,
                     T init,
                     BinaryOperation1 binary_op1,
                     BinaryOperation2 binary_op2);

Requires:

(2.1)
T shall be MoveConstructible (Table 23).
(2.2)
All of
- (2.2.1)
  binary_op1(init, init),
- (2.2.2)
  binary_op1(init, binary_op2(*first1, *first2)),
- (2.2.3)
  binary_op1(binary_op2(*first1, *first2), init), and
- (2.2.4)
  binary_op1(binary_op2(*first1, *first2), binary_op2(*first1, *first2))
shall be convertible to T.
(2.3)
Neither binary_op1 nor binary_op2 shall invalidate subranges, or modify elements in the ranges [first1, last1] and [first2, first2 + (last1 - first1)].

Returns:

GENERALIZED_SUM(binary_op1, init, binary_op2(*i, *(first2 + (i - first1))), ...)

for every iterator i in [first1, last1).

Complexity: applications each of binary_op1 and binary_op2.

template<class InputIterator, class T,
         class BinaryOperation, class UnaryOperation>
  T transform_reduce(InputIterator first, InputIterator last, T init,
                     BinaryOperation binary_op, UnaryOperation unary_op);
template<class ExecutionPolicy,
         class ForwardIterator, class T,
         class BinaryOperation, class UnaryOperation>
  T transform_reduce(ExecutionPolicy&& exec,
                     ForwardIterator first, ForwardIterator last,
                     T init, BinaryOperation binary_op, UnaryOperation unary_op);

Requires:

(5.1)
T shall be MoveConstructible (Table 23).
(5.2)
All of
- (5.2.1)
  binary_op(init, init),
- (5.2.2)
  binary_op(init, unary_op(*first)),
- (5.2.3)
  binary_op(unary_op(*first), init), and
- (5.2.4)
  binary_op(unary_op(*first), unary_op(*first))
shall be convertible to T.
(5.3)
Neither unary_op nor binary_op shall invalidate subranges, or modify elements in the range [first, last].

Returns:

GENERALIZED_SUM(binary_op, init, unary_op(*i), ...)

for every iterator i in [first, last).

Complexity: applications each of unary_op and binary_op.

[ Note

transform_reduce does not apply unary_op to init.

— end note

]