使用PPL在数组中查找最大元素

Question

我需要实现一个函数，它将使用ppl.h在浮点数数组中找到最大的元素。

我有这段代码，基于this answer

float find_largest_element_in_matrix_PPL(float* m, size_t dims)
{
    float max_element;
    int row, col;
    concurrency::combinable<float> locals([] { return INT_MIN + 0.f; });
    concurrency::parallel_for_each(size_t(0), dims * dims, [&locals](int curr)
    {
        float & localMax = locals.local();
        localMax = max<float>(localMax, curr);
    });

    max_element = locals.combine([](float left, float right) { return max<float>(left, right); });
    cout << max_element << endl;
    return max_element;
}

但是，这段代码存在一个问题：

• 它在执行之前抛出以下异常：

错误C2780 'void Concurrency::_Parallel_for_each_impl(const _Random_iterator &，const _Random_iterator &，const _Function &，_Partitioner &，std::random_access_iterator_tag)'：期望5个参数--4个提供parp：\Microsoft 14.0\VC\include\ppl.h 2987 Error C2780 'void C2780 const _Forward_iterator &，const _Function &，const Concurrency::auto_partitioner &，std：：forward_iterator_tag]：期望5个参数--4个提供parp：\MicrosoftVisualStudio14.0\VC\include\ppl.h 2987 错误C2893未能专门化函数模板'iterator_traits<_Iter>::iterator_category std::_Iter_cat(const _Iter &)‘parp D:\Microsoft 14.0\VC\include\ppl.h 2987

1. 你能帮我解决这个问题吗？
2. 如何重写代码以利用parallel_for？(我不能引用传递给parallel_for块中函数的数组参数)

Answer 1

float SimpleTest::SimpleTestfind_largest_element_in_matrix_PPL(float* m, size_t dims)
{
    float max_element;
    concurrency::combinable<float> locals([&]{ return INT_MIN + 0.f; });
    int last= dims*dims;
    concurrency::parallel_for(0, last, [&](int curr)
    {
        float & localMax = locals.local();
        localMax = max<float>(localMax, curr);
    });

    max_element = locals.combine([](float left, float right) { return max<float>(left, right); });
    std::cout << max_element << endl;
    return max_element;
}

也许它会有用