thrust::inclusive_scan

Defined in thrust/scan.h

template<typename DerivedPolicy, typename InputIterator, typename OutputIterator, typename T, typename AssociativeOperator> OutputIterator thrust::inclusive_scan(const thrust::detail::execution_policy_base<DerivedPolicy> &exec, InputIterator first, InputIterator last, OutputIterator result, T init, AssociativeOperator binary_op)

inclusive_scan computes an inclusive prefix sum operation. The term ‘inclusive’ means that each result includes the corresponding input operand in the partial sum. More precisely, binary_op(init, *first) is assigned to *result and so on. This version of inclusive_scan requires both an associative operator and an initial value init. When the input and output sequences are the same, the scan is performed in-place.

Results are not deterministic for pseudo-associative operators (e.g., addition of floating-point types). Results for pseudo-associative operators may vary from run to run.

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

The following code snippet demonstrates how to use inclusive_scan with initial value to compute an in-place prefix sum using the thrust::host execution policy for parallelization:

int data[10] = {-5, 0, 2, -3, 2, 4, 0, -1, 2, 8};
thrust::inclusive_scan(thrust::host, data, data + 10, data, 1, thrust::maximum<>{}); // in-place scan
// data is now {1, 1, 2, 2, 2, 4, 4, 4, 4, 8}