Question

我需要实现一个函数，它可以使用ppl.h找到浮点数组中的最大元素。

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，此代码存在问题：

在执行之前抛出以下异常：

错误C2780＆＃39; void Concurrency :: _ Parallel_for_each_impl（const   _Random_iterator＆amp;，const _Random_iterator＆amp;，const _Function＆amp;，_ Partitioner＆amp;＆amp;，std :: random_access_iterator_tag）＆＃39;：预计5   参数 - 4提供了parp D：\ Microsoft Visual Studio   14.0 \ VC \ include \ ppl.h 2987

错误C2780＆＃39; void Concurrency :: _ Parallel_for_each_impl（_Forward_iterator，const   _Forward_iterator＆amp;，const _Function＆amp;，const Concurrency :: auto_partitioner＆amp;，std :: forward_iterator_tag）＆＃39;：预计5   参数 - 4提供了parp D：\ Microsoft Visual Studio   14.0 \ VC \ include \ ppl.h 2987

错误C2893无法专门化功能模板＆＃39; iterator_traits＆lt; _Iter＆gt; :: iterator_category   std :: _ Iter_cat（const _Iter＆amp;）＆＃39; parp D：\ Microsoft Visual Studio   14.0 \ VC \ include \ ppl.h 2987

你能帮我解决一下这个问题吗？
如何重写代码以使用parallel_for？（我无法引用传递给parallel_for块中的函数的数组参数）

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;
}

也许会起作用

使用PPL在数组中查找max元素

1 个答案: