thrust::adjacent_difference

Defined in thrust/adjacent_difference.h

template<typename DerivedPolicy, typename InputIterator, typename OutputIterator>
OutputIterator thrust::adjacent_difference(const thrust::detail::execution_policy_base<DerivedPolicy> &exec, InputIterator first, InputIterator last, OutputIterator result)

adjacent_difference calculates the differences of adjacent elements in the range [first, last). That is, *first is assigned to *result, and, for each iterator i in the range [first + 1, last), the difference of *i and *(i - 1) is assigned to *(result + (i - first)).

This version of adjacent_difference uses operator- to calculate differences.

The algorithm’s execution is parallelized as determined by exec.

The following code snippet demonstrates how to use adjacent_difference to compute the difference between adjacent elements of a range using the thrust::device execution policy:

Remark

Note that result is permitted to be the same iterator as first. This is useful for computing differences “in place”.

#include <thrust/adjacent_difference.h>
#include <thrust/device_vector.h>
#include <thrust/execution_policy.h>
...
int h_data[8] = {1, 2, 1, 2, 1, 2, 1, 2};
thrust::device_vector<int> d_data(h_data, h_data + 8);
thrust::device_vector<int> d_result(8);

thrust::adjacent_difference(thrust::device, d_data.begin(), d_data.end(), d_result.begin());

// d_result is now [1, 1, -1, 1, -1, 1, -1, 1]

See also

inclusive_scan

Parameters
  • exec – The execution policy to use for parallelization.

  • first – The beginning of the input range.

  • last – The end of the input range.

  • result – The beginning of the output range.

Template Parameters
  • DerivedPolicy – The name of the derived execution policy.

  • InputIterator – is a model of Input Iterator, and x and y are objects of InputIterator's value_type, then x - is defined, and InputIterator's value_type is convertible to a type in OutputIterator's set of value_types, and the return type of x - y is convertible to a type in OutputIterator's set of value_types.

  • OutputIterator – is a model of Output Iterator.

Returns

The iterator result + (last - first)