{

// source vectors

const RVector<double> x;

const RVector<double> y;

// product that I have accumulated

double product;

// constructors

InnerProduct(const NumericVector x, const NumericVector y)

: x(x), y(y), product(0) {}

InnerProduct(const InnerProduct& innerProduct, Split)

: x(innerProduct.x), y(innerProduct.y), product(0) {}

// process just the elements of the range I have been asked to

void operator()(std::size_t begin, std::size_t end) {

product += std::inner_product(x.begin() + begin,

x.begin() + end,

y.begin() + begin,

0.0);

}

// join my value with that of another InnerProduct

void join(const InnerProduct& rhs) {

product += rhs.product;

}

// declare the InnerProduct instance that takes a pointer to the vector data

InnerProduct innerProduct(x, y);

// call paralleReduce to start the work

parallelReduce(0, x.length(), innerProduct);

// return the computed product

return innerProduct.product;