std::exclusive_scan (3) - Linux Man Pages
std::exclusive_scan - std::exclusive_scan
Defined in header <numeric>
template< class InputIt, class OutputIt, class T >
OutputIt exclusive_scan( InputIt first, InputIt last, (1) (since C++17)
OutputIt d_first, T init );
template< class ExecutionPolicy, class ForwardIt1, class ForwardIt2, class T >
ForwardIt2 exclusive_scan( ExecutionPolicy&& policy, ForwardIt1 first, ForwardIt1 last, (2) (since C++17)
ForwardIt2 d_first, T init);
template< class InputIt, class OutputIt,
class T, class BinaryOperation > (3) (since C++17)
OutputIt exclusive_scan( InputIt first, InputIt last,
OutputIt d_first, T init, BinaryOperation binary_op );
template< class ExecutionPolicy, class ForwardIt1, class ForwardIt2,
class T, class BinaryOperation > (4) (since C++17)
ForwardIt2 exclusive_scan( ExecutionPolicy&& policy, ForwardIt1 first, ForwardIt1 last,
ForwardIt2 d_first, T init, BinaryOperation binary_op );
Computes an exclusive prefix sum operation using binary_op (or std::plus<>() for overloads (1-2)) for the range [first, last), using init as the initial value, and writes the results to the range beginning at d_first. "exclusive" means that the i-th input element is not included in the i-th sum.
Formally, assigns through each iterator i in [d_first, d_first + (last - first)) the value of the generalized noncommutative sum of init, *j... for every j in [first, first + (i - d_first)) over binary_op,
where generalized noncommutative sum GNSUM(op, a
1, ..., a
N) is defined as follows:
* if N=1, a
* if N > 1, op(GNSUM(op, a
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. This overload only participates in overload resolution if std::is_execution_policy_v<std::decay_t<ExecutionPolicy>> is true.
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
binary_op - binary FunctionObject that will be applied in to the result of dereferencing the input iterators, the results of other binary_op, and init.
InputIt must meet the requirements of LegacyInputIterator.
OutputIt must meet the requirements of LegacyOutputIterator.
ForwardIt1, ForwardIt2 must meet the requirements of LegacyForwardIterator.
T must meet the requirements of MoveConstructible. and binary_op(init, *first), binary_op(init, init), and binary_op(*first, *first) must be convertible to T
Iterator to the element past the last element written.
O(last - first) applications of the binary operation
The overloads with a template parameter named ExecutionPolicy report errors as follows:
* If execution of a function invoked as part of the algorithm throws an exception and ExecutionPolicy is one of the standard_policies, std::terminate is called. For any other ExecutionPolicy, the behavior is implementation-defined.
* If the algorithm fails to allocate memory, std::bad_alloc is thrown.
// Run this code
std::ostream_iterator<int>(std::cout, " "),
adjacent_difference (function template)
accumulate (function template)
partial_sum (function template)
transform_exclusive_scan applies a functor, then calculates exclusive scan
inclusive_scan similar to std::partial_sum, includes the ith input element in the ith sum