exclusive_scan
computes an exclusive prefix sum operation. The term 'exclusive' means that each result does not include the corresponding input operand in the partial sum. More precisely, init
is assigned to *result
and the sum of init
and *first
is assigned to *(result + 1)
, and so on. This version of exclusive_scan
assumes plus as the associative operator but requires 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.
- Parameters
-
first | The beginning of the input sequence. |
last | The end of the input sequence. |
result | The beginning of the output sequence. |
init | The initial value. |
- Returns
- The end of the output sequence.
- Template Parameters
-
InputIterator | is a model of Input Iterator and InputIterator's value_type is convertible to OutputIterator's value_type . |
OutputIterator | is a model of Output Iterator, and if x and y are objects of OutputIterator's value_type , then x + y is defined. |
T | is convertible to OutputIterator's value_type . |
- Precondition
first
may equal result
but the range [first, last)
and the range [result, result + (last - first))
shall not overlap otherwise.
The following code snippet demonstrates how to use exclusive_scan
#include <thrust/scan.h>
int data[6] = {1, 0, 2, 2, 1, 3};
- See also
- https://en.cppreference.com/w/cpp/algorithm/partial_sum