Defined in header <numeric>  

template< class InputIt, class OutputIt, class BinaryOperation, class UnaryOperation > OutputIt transform_inclusive_scan( InputIt first, InputIt last, OutputIt d_first, BinaryOperation binary_op, UnaryOperation unary_op );  (1)  (since C++17) 
template< class ExecutionPolicy, class ForwardIt1, class ForwardIt2, class BinaryOperation, class UnaryOperation > ForwardIt2 transform_inclusive_scan( ExecutionPolicy&& policy, ForwardIt1 first, ForwardIt1 last, ForwardIt2 d_first, BinaryOperation binary_op, UnaryOperation unary_op );  (2)  (since C++17) 
template< class InputIt, class OutputIt, class BinaryOperation, class UnaryOperation, class T > OutputIt transform_inclusive_scan( InputIt first, InputIt last, OutputIt d_first, BinaryOperation binary_op, UnaryOperation unary_op, T init );  (3)  (since C++17) 
template< class ExecutionPolicy, class ForwardIt1, class ForwardIt2, class BinaryOperation, class UnaryOperation, class T > ForwardIt2 transform_inclusive_scan( ExecutionPolicy&& policy, ForwardIt1 first, ForwardIt1 last, ForwardIt2 d_first, BinaryOperation binary_op, UnaryOperation unary_op, T init );  (4)  (since C++17) 
Transforms each element in the range [first, last)
with unary_op
, then computes an inclusive prefix sum operation using binary_op
over the resulting range, optionally with init
as the initial value, and writes the results to the range beginning at d_first
. "inclusive" means that the ith input element is included in the ith sum.
Formally, assigns through each iterator i
in [d_first, d_first + (last  first)) the value of.
unary_op(*j)...
for every j
in [first, first + (i  d_first + 1)) over binary_op
, init, unary_op(*j)...
for every j
in [first, first + (i  d_first + 1)) over binary_op
, where generalized noncommutative sum GNSUM(op, a
1, ..., a
N) is defined as follows:
In other words, the summation operations may be performed in arbitrary order, and the behavior is nondeterministic if binary_op
is not associative.
Overloads (2, 4) are executed according to policy
, and do not participate in overload resolution unless std::is_execution_policy_v<std::decay_t<ExecutionPolicy>>
is true.
unary_op
and binary_op
shall not invalidate iterators (including the end iterators) or subranges, nor modify elements in the ranges [first, last) or [d_first, d_first + (last  first)). Otherwise, the behavior is undefined.
first, last    the range of elements to sum 
d_first    the beginning of the destination range; may be equal to first 
policy    the execution policy to use. See execution policy for details. 
init    the initial value 
unary_op    unary FunctionObject that will be applied to each element of the input range. The return type must be acceptable as input to binary_op . 
binary_op    binary FunctionObject that will be applied in to the result of unary_op , the results of other binary_op , and init if provided. 
Type requirements  
InputIt must meet the requirements of InputIterator . 

OutputIt must meet the requirements of OutputIterator . 

ForwardIt1 must meet the requirements of ForwardIterator . and, if init is not provided, ForwardIt1's value_type must be MoveConstructible and binary_op(unary_op(*first), unary_op(*first)) must be convertible to ForwardIt1's value type 

ForwardIt2 must meet the requirements of ForwardIterator . 

T (if init is provided) must meet the requirements of MoveConstructible . All of binary_op(init, unary_op(*first)) , binary_op(init, init) , and binary_op(unary_op(*first), unary_op(*first)) must be convertible to T 
Iterator to the element past the last element written.
O(last  first) applications of each of binary_op
and unary_op
.
The overloads with a template parameter named ExecutionPolicy
report errors as follows:
ExecutionPolicy
is one of the three standard policies, std::terminate
is called. For any other ExecutionPolicy
, the behavior is implementationdefined. std::bad_alloc
is thrown. unary_op
is not applied to init
.
The parameter init
appears last, differing from std::transform_exclusive_scan
, because it is optional for this function.
computes the partial sum of a range of elements (function template) 

applies a function to a range of elements (function template) 

(C++17)  similar to std::partial_sum , includes the ith input element in the ith sum (function template) 
(C++17)  applies a functor, then calculates exclusive scan (function template) 
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