Template Function thrust::inner_product(InputIterator1, InputIterator1, InputIterator2, OutputType)

Function Documentation

template<typename InputIterator1, typename InputIterator2, typename OutputType>
OutputType thrust::inner_product(InputIterator1 first1, InputIterator1 last1, InputIterator2 first2, OutputType init)

inner_product calculates an inner product of the ranges [first1, last1) and [first2, first2 + (last1 - first1)).

Specifically, this version of inner_product computes the sum init + (*first1 * *first2) + (*(first1+1) * *(first2+1)) + ...

Unlike the C++ Standard Template Library function std::inner_product, this version offers no guarantee on order of execution.

The following code demonstrates how to use

inner_product to compute the dot product of two vectors.

Return

The inner product of sequences [first1, last1) and [first2, last2) plus init.

Parameters

• first1: The beginning of the first sequence.

• last1: The end of the first sequence.

• first2: The beginning of the second sequence.

• init: Initial value of the result.

Template Parameters

• InputIterator1: is a model of Input Iterator,

• InputIterator2: is a model of Input Iterator,

• OutputType: is a model of Assignable, and if x is an object of type OutputType, and y is an object of InputIterator1's value_type, and z is an object of InputIterator2's value_type, then x + y * z is defined and is convertible to OutputType.

#include <thrust/inner_product.h>
...
float vec1[3] = {1.0f, 2.0f, 5.0f};
float vec2[3] = {4.0f, 1.0f, 5.0f};

float result = thrust::inner_product(vec1, vec1 + 3, vec2, 0.0f);

// result == 31.0f

See

http://www.sgi.com/tech/stl/inner_product.html