CL-reduce

Functions
template<typename InputIterator >
std::iterator_traits < InputIterator >::value_type	bolt::cl::reduce (bolt::cl::control &ctl, InputIterator first, InputIterator last, const std::string &cl_code="")
	reduce returns the result of combining all the elements in the specified range using the specified binary_op. The classic example is a summation, where the binary_op is the plus operator. By default, the initial value is "0" and the binary operator is "plus<>()".
template<typename InputIterator >
std::iterator_traits < InputIterator >::value_type	bolt::cl::reduce (InputIterator first, InputIterator last, const std::string &cl_code="")
template<typename InputIterator , typename T >
T	bolt::cl::reduce (bolt::cl::control &ctl, InputIterator first, InputIterator last, T init, const std::string &cl_code="")
	reduce returns the result of combining all the elements in the specified range using the specified binary_op. The classic example is a summation, where the binary_op is the plus operator. By default, the initial value is "0" and the binary operator is "plus<>()".
template<typename InputIterator , typename T >
T	bolt::cl::reduce (InputIterator first, InputIterator last, T init, const std::string &cl_code="")
template<typename InputIterator , typename T , typename BinaryFunction >
T	bolt::cl::reduce (bolt::cl::control &ctl, InputIterator first, InputIterator last, T init, BinaryFunction binary_op=bolt::cl::plus< T >(), const std::string &cl_code="")
	reduce returns the result of combining all the elements in the specified range using the specified binary_op. The classic example is a summation, where the binary_op is the plus operator. By default, the binary operator is "plus<>()". The version takes a bolt::cl::control structure as a first argument.
template<typename InputIterator , typename T , typename BinaryFunction >
T	bolt::cl::reduce (InputIterator first, InputIterator last, T init, BinaryFunction binary_op, const std::string &cl_code="")

Detailed Description

Function Documentation

template<typename InputIterator >

std::iterator_traits< InputIterator >::value_type bolt::cl::reduce	(	bolt::cl::control &	ctl,
		InputIterator	first,
		InputIterator	last,
		const std::string &	cl_code = ""
	)

reduce returns the result of combining all the elements in the specified range using the specified binary_op. The classic example is a summation, where the binary_op is the plus operator. By default, the initial value is "0" and the binary operator is "plus<>()".

reduce requires that the binary reduction op ("binary_op") be commutative. The order in which reduce applies the binary_op is not deterministic. If the reduction operator is not commutative then bolt::reduce should not be used. Instead, one could use inclusive_scan (which does not require commutativity) and select the last element of the output array.

The reduce operation is similar the std::accumulate function

Parameters

ctl	Optional Control structure to control command-queue, debug, tuning.
first	The first position in the sequence to be reduced.
last	The last position in the sequence to be reduced.
cl_code	Optional OpenCL(TM) code to be passed to the OpenCL compiler. The cl_code is inserted first in the generated code, before the cl_code trait.

Template Parameters

InputIterator	An iterator that can be dereferenced for an object, and can be incremented to get to the next element in a sequence.
T	The type of the result.

Returns

The result of the reduction.

The following code example shows the use of reduce to sum 10 numbers, using the default plus operator.

#include <bolt/cl/reduce.h>

int a[10] = {1, 2, 3, 4, 5, 6, 7, 8, 9, 10};


int sum = bolt::cl::reduce(a, a+10);
// sum = 55

See Also

http://www.sgi.com/tech/stl/accumulate.html

template<typename InputIterator , typename T >

T bolt::cl::reduce	(	bolt::cl::control &	ctl,
		InputIterator	first,
		InputIterator	last,
		T	init,
		const std::string &	cl_code = ""
	)

reduce returns the result of combining all the elements in the specified range using the specified binary_op. The classic example is a summation, where the binary_op is the plus operator. By default, the initial value is "0" and the binary operator is "plus<>()".

reduce requires that the binary reduction op ("binary_op") be commutative. The order in which reduce applies the binary_op is not deterministic. If the reduction operator is not commutative then bolt::reduce should not be used. Instead, one could use inclusive_scan (which does not require commutativity) and select the last element of the output array.

The reduce operation is similar the std::accumulate function

Parameters

ctl	Optional Control structure to control command-queue, debug, tuning.
first	The first position in the sequence to be reduced.
last	The last position in the sequence to be reduced.
init	The initial value for the accumulator.
cl_code	Optional OpenCL(TM) code to be passed to the OpenCL compiler. The cl_code is inserted first in the generated code, before the cl_code trait.

Template Parameters

InputIterator	An iterator that can be dereferenced for an object, and can be incremented to get to the next element in a sequence.
T	The type of the result.

Returns

The result of the reduction.

The following code example shows the use of reduce to sum 10 numbers, using the default plus operator.

#include <bolt/cl/reduce.h>

int a[10] = {1, 2, 3, 4, 5, 6, 7, 8, 9, 10};

int init = 10;

int sum = bolt::cl::reduce(a, a+10, init);
// sum = 65

See Also

http://www.sgi.com/tech/stl/accumulate.html

template<typename InputIterator , typename T , typename BinaryFunction >

T bolt::cl::reduce	(	bolt::cl::control &	ctl,
		InputIterator	first,
		InputIterator	last,
		T	init,
		BinaryFunction	binary_op = bolt::cl::plus<T>(),
		const std::string &	cl_code = ""
	)

reduce returns the result of combining all the elements in the specified range using the specified binary_op. The classic example is a summation, where the binary_op is the plus operator. By default, the binary operator is "plus<>()". The version takes a bolt::cl::control structure as a first argument.

reduce requires that the binary reduction op ("binary_op") be commutative. The order in which reduce applies the binary_op is not deterministic. If the reduction operator is not commutative then bolt::reduce should not be used. Instead, one could use inclusive_scan (which does not require commutativity) and select the last element of the output array.

The reduce operation is similar the std::accumulate function.

Parameters

ctl	Optional Control structure to control command-queue, debug, tuning, etc.
first	The first position in the sequence to be reduced.
last	The last position in the sequence to be reduced.
init	The initial value for the accumulator.
binary_op	The binary operation used to combine two values. By default, the binary operation is plus<>().
cl_code	Optional OpenCL(TM) code to be passed to the OpenCL compiler. The cl_code is inserted first in the generated code, before the cl_code trait.

Template Parameters

InputIterator	An iterator that can be dereferenced for an object, and can be incremented to get to the next element in a sequence.
BinaryFunction	A function object defining an operation that is applied to consecutive elements in the sequence.

Returns

The result of the reduction.

The following code example shows the use of reduce to find the max of 10 numbers.

#include <bolt/cl/reduce.h>

int a[10] = {2, 9, 3, 7, 5, 6, 3, 8, 3, 4};

int max = bolt::cl::reduce( a, a+10, -1, bolt::cl:maximum<int>());
// max = 9

See Also

http://www.sgi.com/tech/stl/accumulate.html