Defined in header
template< class InputIt, class OutputIt, class T,
class BinaryOperation, class UnaryOperation>
template< class ExecutionPolicy,
class ForwardIt1, class ForwardIt2,
Transforms each element in the range
[first, last) with
unary_op, then computes an exclusive prefix sum operation using
binary_op over the resulting range, with
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, unary_op(*j)... for every
j in [first, first + (i - d_first)) over
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
1, ..., a
K), GNSUM(op, a
M, ..., a
N)) for any K where 1 < K+1 = M ≤ N
In other words, the summation operations may be performed in arbitrary order, and the behavior is nondeterministic if
binary_op is not associative.
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 |
|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 FunctionObject that will be applied in to the result of |
Iterator to the element past the last element written.
O(last - first) applications of each of
The overload with a template parameter named
ExecutionPolicy reports errors as follows:
- If execution of a function invoked as part of the algorithm throws an exception and
ExecutionPolicyis one of the three 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.
unary_op is not applied to
|This section is incomplete|
Reason: no example
| computes the partial sum of a range of elements |
| similar to std::partial_sum, excludes the ith input element from the ith sum |
| applies a functor, then calculates inclusive scan |