cub::DeviceAdjacentDifference Struct Reference

Detailed description

DeviceAdjacentDifference provides device-wide, parallel operations for computing the differences of adjacent elements residing within device-accessible memory.

Overview

• DeviceAdjacentDifference calculates the differences of adjacent elements in d_input. Because the binary operation could be noncommutative, there are two sets of methods. Methods named SubtractLeft subtract left element *(i - 1) of input sequence from current element *i. Methods named SubtractRight subtract current element *i from the right one *(i + 1):

int *d_values; // [1, 2, 3, 4]
//...
int *d_subtract_left_result  <-- [  1,  1,  1,  1 ]
int *d_subtract_right_result <-- [ -1, -1, -1,  4 ]

• For SubtractLeft, if the left element is out of bounds, the iterator is assigned to *(result + (i - first)) without modification.
• For SubtractRight, if the right element is out of bounds, the iterator is assigned to *(result + (i - first)) without modification.

Snippet

The code snippet below illustrates how to use DeviceAdjacentDifference to compute the left difference between adjacent elements.

#include <cub/cub.cuh>
// or equivalently <cub/device/device_adjacent_difference.cuh>

// Declare, allocate, and initialize device-accessible pointers
int  num_items;       // e.g., 8
int  *d_values;       // e.g., [1, 2, 1, 2, 1, 2, 1, 2]
//...

// Determine temporary device storage requirements
void     *d_temp_storage = NULL;
size_t   temp_storage_bytes = 0;

cub::DeviceAdjacentDifference::SubtractLeft(
  d_temp_storage, temp_storage_bytes, d_values, num_items);

// Allocate temporary storage
cudaMalloc(&d_temp_storage, temp_storage_bytes);

// Run operation
cub::DeviceAdjacentDifference::SubtractLeft(
  d_temp_storage, temp_storage_bytes, d_values, num_items);

// d_values <-- [1, 1, -1, 1, -1, 1, -1, 1]

Static Public Methods
template<typename InputIteratorT , typename OutputIteratorT , typename DifferenceOpT = cub::Difference>
static CUB_RUNTIME_FUNCTION cudaError_t	SubtractLeftCopy (void *d_temp_storage, std::size_t &temp_storage_bytes, InputIteratorT d_input, OutputIteratorT d_output, std::size_t num_items, DifferenceOpT difference_op={}, cudaStream_t stream=0, bool debug_synchronous=false)
	Subtracts the left element of each adjacent pair of elements residing within device-accessible memory. More...
template<typename RandomAccessIteratorT , typename DifferenceOpT = cub::Difference>
static CUB_RUNTIME_FUNCTION cudaError_t	SubtractLeft (void *d_temp_storage, std::size_t &temp_storage_bytes, RandomAccessIteratorT d_input, std::size_t num_items, DifferenceOpT difference_op={}, cudaStream_t stream=0, bool debug_synchronous=false)
	Subtracts the left element of each adjacent pair of elements residing within device-accessible memory. More...
template<typename InputIteratorT , typename OutputIteratorT , typename DifferenceOpT = cub::Difference>
static CUB_RUNTIME_FUNCTION cudaError_t	SubtractRightCopy (void *d_temp_storage, std::size_t &temp_storage_bytes, InputIteratorT d_input, OutputIteratorT d_output, std::size_t num_items, DifferenceOpT difference_op={}, cudaStream_t stream=0, bool debug_synchronous=false)
	Subtracts the right element of each adjacent pair of elements residing within device-accessible memory. More...
template<typename RandomAccessIteratorT , typename DifferenceOpT = cub::Difference>
static CUB_RUNTIME_FUNCTION cudaError_t	SubtractRight (void *d_temp_storage, std::size_t &temp_storage_bytes, RandomAccessIteratorT d_input, std::size_t num_items, DifferenceOpT difference_op={}, cudaStream_t stream=0, bool debug_synchronous=false)
	Subtracts the right element of each adjacent pair of elements residing within device-accessible memory. More...

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The documentation for this struct was generated from the following file:

• device_adjacent_difference.cuh