hpx/parallel/algorithms/transform_inclusive_scan.hpp#

See Public API for a list of names and headers that are part of the public HPX API.

namespace hpx

Functions

template<typename InIter, typename OutIter, typename BinOp, typename UnOp>
OutIter transform_inclusive_scan(InIter first, InIter last, OutIter dest, BinOp &&binary_op, UnOp &&unary_op)#

Assigns through each iterator i in [result, result + (last - first)) the value of GENERALIZED_NONCOMMUTATIVE_SUM(op, conv(*first), …, conv(*(first + (i - result)))).

The reduce operations in the parallel transform_inclusive_scan algorithm invoked without an execution policy object execute in sequential order in the calling thread.

Neither binary_op nor unary_op shall invalidate iterators or subranges, or modify elements in the ranges [first,last) or [result,result + (last - first)).

The difference between inclusive_scan and transform_inclusive_scan is that transform_inclusive_scan includes the ith input element in the ith sum.

Note

Complexity: O(last - first) applications of each of binary_op and unary_op.

Note

GENERALIZED_NONCOMMUTATIVE_SUM(op, a1, …, aN) is defined as:

  • a1 when N is 1

  • op(GENERALIZED_NONCOMMUTATIVE_SUM(op, a1, …, aK), GENERALIZED_NONCOMMUTATIVE_SUM(op, aM, …, aN)) where 1 < K+1 = M <= N.

Template Parameters
  • InIter – The type of the source iterators used (deduced). This iterator type must meet the requirements of an input iterator.

  • OutIter – The type of the iterator representing the destination range (deduced). This iterator type must meet the requirements of an output iterator.

  • BinOp – The type of binary_op.

  • UnOp – The type of unary_op.

Parameters
  • first – Refers to the beginning of the sequence of elements the algorithm will be applied to.

  • last – Refers to the end of the sequence of elements the algorithm will be applied to.

  • dest – Refers to the beginning of the destination range.

  • 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.

  • 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.

Returns

The transform_inclusive_scan algorithm returns a returns OutIter. The transform_inclusive_scan algorithm returns the output iterator to the element in the destination range, one past the last element copied.

template<typename ExPolicy, typename FwdIter1, typename FwdIter2, typename BinOp, typename UnOp>
parallel::util::detail::algorithm_result<ExPolicy, FwdIter2>::type transform_inclusive_scan(ExPolicy &&policy, FwdIter1 first, FwdIter1 last, FwdIter2 dest, BinOp &&binary_op, UnOp &&unary_op)#

Assigns through each iterator i in [result, result + (last - first)) the value of GENERALIZED_NONCOMMUTATIVE_SUM(op, conv(*first), …, conv(*(first + (i - result)))). Executed according to the policy.

The reduce operations in the parallel transform_inclusive_scan algorithm invoked with an execution policy object of type sequenced_policy execute in sequential order in the calling thread.

The reduce operations in the parallel transform_inclusive_scan algorithm invoked with an execution policy object of type parallel_policy or parallel_task_policy are permitted to execute in an unordered fashion in unspecified threads, and indeterminately sequenced within each thread.

Neither binary_op nor unary_op shall invalidate iterators or subranges, or modify elements in the ranges [first,last) or [result,result + (last - first)).

The difference between inclusive_scan and transform_inclusive_scan is that transform_inclusive_scan includes the ith input element in the ith sum.

Note

Complexity: O(last - first) applications of each of binary_op and unary_op.

Note

GENERALIZED_NONCOMMUTATIVE_SUM(op, a1, …, aN) is defined as:

  • a1 when N is 1

  • op(GENERALIZED_NONCOMMUTATIVE_SUM(op, a1, …, aK), GENERALIZED_NONCOMMUTATIVE_SUM(op, aM, …, aN)) where 1 < K+1 = M <= N.

Template Parameters
  • ExPolicy – The type of the execution policy to use (deduced). It describes the manner in which the execution of the algorithm may be parallelized and the manner in which it executes the assignments.

  • FwdIter1 – The type of the source iterators used (deduced). This iterator type must meet the requirements of a forward iterator.

  • FwdIter2 – The type of the iterator representing the destination range (deduced). This iterator type must meet the requirements of a forward iterator.

  • BinOp – The type of binary_op.

  • UnOp – The type of unary_op.

Parameters
  • policy – The execution policy to use for the scheduling of the iterations.

  • first – Refers to the beginning of the sequence of elements the algorithm will be applied to.

  • last – Refers to the end of the sequence of elements the algorithm will be applied to.

  • dest – Refers to the beginning of the destination range.

  • 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.

  • unnary_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.

Returns

The transform_inclusive_scan algorithm returns a hpx::future<FwdIter2> if the execution policy is of type sequenced_task_policy or parallel_task_policy and returns FwdIter2 otherwise. The transform_inclusive_scan algorithm returns the output iterator to the element in the destination range, one past the last element copied.

template<typename InIter, typename OutIter, typename BinOp, typename UnOp, typename T = typename std::iterator_traits<InIter>::value_type>
OutIter transform_inclusive_scan(InIter first, InIter last, OutIter dest, BinOp &&binary_op, UnOp &&unary_op, T init)#

Assigns through each iterator i in [result, result + (last - first)) the value of GENERALIZED_NONCOMMUTATIVE_SUM(op, init, conv(*first), …, conv(*(first + (i - result)))).

The reduce operations in the parallel transform_inclusive_scan algorithm invoked without an execution policy object execute in sequential order in the calling thread.

Neither binary_op nor unary_op shall invalidate iterators or subranges, or modify elements in the ranges [first,last) or [result,result + (last - first)).

The difference between inclusive_scan and transform_inclusive_scan is that transform_inclusive_scan includes the ith input element in the ith sum. If binary_op is not mathematically associative, the behavior of transform_inclusive_scan may be non-deterministic.

Note

Complexity: O(last - first) applications of each of binary_op and unary_op.

Note

GENERALIZED_NONCOMMUTATIVE_SUM(op, a1, …, aN) is defined as:

  • a1 when N is 1

  • op(GENERALIZED_NONCOMMUTATIVE_SUM(op, a1, …, aK), GENERALIZED_NONCOMMUTATIVE_SUM(op, aM, …, aN)) where 1 < K+1 = M <= N.

Template Parameters
  • InIter – The type of the source iterators used (deduced). This iterator type must meet the requirements of an input iterator.

  • OutIter – The type of the iterator representing the destination range (deduced). This iterator type must meet the requirements of an output iterator.

  • BinOp – The type of binary_op.

  • UnOp – The type of unary_op.

  • T – The type of the value to be used as initial (and intermediate) values (deduced).

Parameters
  • first – Refers to the beginning of the sequence of elements the algorithm will be applied to.

  • last – Refers to the end of the sequence of elements the algorithm will be applied to.

  • dest – Refers to the beginning of the destination range.

  • 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.

  • unnary_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.

  • init – The initial value for the generalized sum.

Returns

The transform_inclusive_scan algorithm returns a returns OutIter. The transform_inclusive_scan algorithm returns the output iterator to the element in the destination range, one past the last element copied.

template<typename ExPolicy, typename FwdIter1, typename FwdIter2, typename BinOp, typename UnOp, typename T = typename std::iterator_traits<FwdIter1>::value_type>
parallel::util::detail::algorithm_result<ExPolicy, FwdIter2>::type transform_inclusive_scan(ExPolicy &&policy, FwdIter1 first, FwdIter1 last, FwdIter2 dest, BinOp &&binary_op, UnOp &&unary_op, T init)#

Assigns through each iterator i in [result, result + (last - first)) the value of GENERALIZED_NONCOMMUTATIVE_SUM(op, init, conv(*first), …, conv(*(first + (i - result)))). Executed according to the policy.

The reduce operations in the parallel transform_inclusive_scan algorithm invoked with an execution policy object of type sequenced_policy execute in sequential order in the calling thread.

The reduce operations in the parallel transform_inclusive_scan algorithm invoked with an execution policy object of type parallel_policy or parallel_task_policy are permitted to execute in an unordered fashion in unspecified threads, and indeterminately sequenced within each thread.

Neither binary_op nor unary_op shall invalidate iterators or subranges, or modify elements in the ranges [first,last) or [result,result + (last - first)).

The difference between inclusive_scan and transform_inclusive_scan is that transform_inclusive_scan includes the ith input element in the ith sum. If binary_op is not mathematically associative, the behavior of transform_inclusive_scan may be non-deterministic.

Note

Complexity: O(last - first) applications of each of binary_op and unary_op.

Note

GENERALIZED_NONCOMMUTATIVE_SUM(op, a1, …, aN) is defined as:

  • a1 when N is 1

  • op(GENERALIZED_NONCOMMUTATIVE_SUM(op, a1, …, aK), GENERALIZED_NONCOMMUTATIVE_SUM(op, aM, …, aN)) where 1 < K+1 = M <= N.

Template Parameters
  • ExPolicy – The type of the execution policy to use (deduced). It describes the manner in which the execution of the algorithm may be parallelized and the manner in which it executes the assignments.

  • FwdIter1 – The type of the source iterators used (deduced). This iterator type must meet the requirements of an forward iterator.

  • FwdIter2 – The type of the iterator representing the destination range (deduced). This iterator type must meet the requirements of an forward iterator.

  • BinOp – The type of binary_op.

  • UnOp – The type of unary_op.

  • T – The type of the value to be used as initial (and intermediate) values (deduced).

Parameters
  • policy – The execution policy to use for the scheduling of the iterations.

  • first – Refers to the beginning of the sequence of elements the algorithm will be applied to.

  • last – Refers to the end of the sequence of elements the algorithm will be applied to.

  • dest – Refers to the beginning of the destination range.

  • 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.

  • unnary_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.

  • init – The initial value for the generalized sum.

Returns

The transform_inclusive_scan algorithm returns a hpx::future<FwdIter2> if the execution policy is of type sequenced_task_policy or parallel_task_policy and returns FwdIter2 otherwise. The transform_inclusive_scan algorithm returns the output iterator to the element in the destination range, one past the last element copied.