bool ParallelComputeAverages(Numbers const &numbers, Averages &averages)
{
if (numbers.empty())
{
return false;
}
// sort numbers for mode and median
Numbers sorted = numbers;
Averages avgResult;
int modeResult;
double medianResult;
// sort numbers for median / mode
tbb::parallel_sort(sorted);
auto medianFunc = [&medianResult, &sorted]()
{
medianResult = ComputeMedian(sorted);
};
auto avgFunc = [&avgResult, &numbers]()
{
auto grainSize = numbers.size() / thread::hardware_concurrency();
Averages avg{0, 0, 0, 0, 0, 0};
avgResult = tbb::parallel_reduce(
Range(numbers.begin(), numbers.end(), grainSize), avg,
CalcIntermediateAverages,
AddIntermediateAverages);
};
auto modeFunc = [&modeResult, &sorted]()
{
modeResult = ComputeMode(sorted);
};
// invoke parallel execution of calculations
tbb::parallel_invoke(avgFunc, modeFunc, medianFunc);
// set result
double size = (double) numbers.size();
averages.arithmeticMean = avgResult.arithmeticMean / size;
averages.geometricMean = exp(avgResult.geometricMean / size);
averages.harmonicMean = size / avgResult.harmonicMean;
averages.quadraticMean = sqrt(avgResult.quadraticMean / size);
averages.mode = modeResult;
averages.median = medianResult;
return true;
}
void iterate() {
printf("size = %d\n", numbers.size());
NumbersIter iter;
for (iter = numbers.begin(); iter != numbers.end(); ++iter) {
printf(" %d\n", *iter);
}
}