reduce_sum

rocThrust sum (reduce) example

Description

An example is presented to compute the sum of a thrust::device_vector integer vector using the thrust::reduce() generalized summation and the thrust::plus operator. The result is written to the standard output.

Application flow

1. Instantiate a thrust::host_vector and fill the elements. The values of the elements are printed to the standard output.
2. Copy the vector to the device by thrust::device_vector.
3. Set the initial value of the reduction.
4. Use the thrust::reduce() generalized summary function with the thrust::plus addition operator and return the sum of the vector.
5. Print the sum to the standard output.

Key APIs and Concepts

• The thrust::reduce() function returns a generalized sum. The summation operator has to be provided by the caller.
• In the example, the operator is the thrust::plus function object with integers. It is a binary operator that returns the arithmetic sum.
• A thrust::device_vector and a thrust::host_vector are used to simplify memory management and transfer. For further details, please visit the vectors example.

Demonstrated API Calls

rocThrust

• thrust::host_vector::host_vector
• thrust::host_vector::operator[]
• thrust::device_vector::device_vector
• thrust::plus::plus
• thrust::reduce()