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 conv nor 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 the predicate 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.
Conv – The type of the unary function object used for the conversion operation.
Op – The type of the binary function object used for the reduction operation.

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.
op – Specifies the function (or function object) which will be invoked for each of the values of the input sequence. This is a binary predicate. The signature of this predicate should be equivalent to:
```
Ret fun(const Type1 &a, const Type1 &b);
```
The signature does not need to have const&, but the function must not modify the objects passed to it. The types Type1 and Ret must be such that an object of a type as given by the input sequence can be implicitly converted to any of those types.
conv – Specifies the function (or function object) which will be invoked for each of the elements in the sequence specified by [first, last). This is a unary predicate. The signature of this predicate should be equivalent to:
```
R fun(const Type &a);
```
The signature does not need to have const&, but the function must not modify the objects passed to it. The type Type must be such that an object of type FwdIter1 can be dereferenced and then implicitly converted to Type. The type R must be such that an object of this type can be implicitly converted to T.

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)))).

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 conv nor 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 the predicate 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.
Conv – The type of the unary function object used for the conversion operation.
Op – The type of the binary function object used for the reduction operation.

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.
op – Specifies the function (or function object) which will be invoked for each of the values of the input sequence. This is a binary predicate. The signature of this predicate should be equivalent to:
```
Ret fun(const Type1 &a, const Type1 &b);
```
The signature does not need to have const&, but the function must not modify the objects passed to it. The types Type1 and Ret must be such that an object of a type as given by the input sequence can be implicitly converted to any of those types.
conv – Specifies the function (or function object) which will be invoked for each of the elements in the sequence specified by [first, last). This is a unary predicate. The signature of this predicate should be equivalent to:
```
R fun(const Type &a);
```
The signature does not need to have const&, but the function must not modify the objects passed to it. The type Type must be such that an object of type FwdIter1 can be dereferenced and then implicitly converted to Type. The type R must be such that an object of this type can be implicitly converted to T.

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> 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 conv nor 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. op is not mathematically associative, the behavior of transform_inclusive_scan may be non-deterministic.

Note

Complexity: O(last - first) applications of the predicate 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.
Conv – The type of the unary function object used for the conversion operation.
Op – The type of the binary function object used for the reduction operation.
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.
op – Specifies the function (or function object) which will be invoked for each of the values of the input sequence. This is a binary predicate. The signature of this predicate should be equivalent to:
```
Ret fun(const Type1 &a, const Type1 &b);
```
The signature does not need to have const&, but the function must not modify the objects passed to it. The types Type1 and Ret must be such that an object of a type as given by the input sequence can be implicitly converted to any of those types.
conv – Specifies the function (or function object) which will be invoked for each of the elements in the sequence specified by [first, last). This is a unary predicate. The signature of this predicate should be equivalent to:
```
R fun(const Type &a);
```
The signature does not need to have const&, but the function must not modify the objects passed to it. The type Type must be such that an object of type FwdIter1 can be dereferenced and then implicitly converted to Type. The type R must be such that an object of this type can be implicitly converted to T.
init – The initial value for the generalized sum.

Returns

template<typename ExPolicy, typename FwdIter1, typename FwdIter2, typename BinOp, typename UnOp, typename T> 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)))).

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.

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

Note

Complexity: O(last - first) applications of the predicate 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.
Conv – The type of the unary function object used for the conversion operation.
Op – The type of the binary function object used for the reduction operation.
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.
op – Specifies the function (or function object) which will be invoked for each of the values of the input sequence. This is a binary predicate. The signature of this predicate should be equivalent to:
```
Ret fun(const Type1 &a, const Type1 &b);
```
The signature does not need to have const&, but the function must not modify the objects passed to it. The types Type1 and Ret must be such that an object of a type as given by the input sequence can be implicitly converted to any of those types.
conv – Specifies the function (or function object) which will be invoked for each of the elements in the sequence specified by [first, last). This is a unary predicate. The signature of this predicate should be equivalent to:
```
R fun(const Type &a);
```
The signature does not need to have const&, but the function must not modify the objects passed to it. The type Type must be such that an object of type FwdIter1 can be dereferenced and then implicitly converted to Type. The type R must be such that an object of this type can be implicitly converted to T.
init – The initial value for the generalized sum.

Returns