#include <algorithm>
    #include <iostream>
    #include <array>
 
    long* IndexSort(unsigned long int vectorLength, double* column)
    {
        long *index = new long[vectorLength](); // I really don't recommend this line
        long n = 0;
        std::generate( index, index + vectorLength, [&] { return n++; });
        std::sort(index, index + vectorLength, [&](long v1, long v2) 
                 { return column[v1] < column[v2]; });
        return index;
    }
 
    using namespace std;
 
    int main()
    {  
      std::array<double,20> testData = 
                            {0.8147,0.9058,0.127,0.9134,0.6324,0.0975,0.2785,
                            0.5469,0.9575,0.9649,0.1576,0.9706,0.9572,0.4854,
                            0.8003,0.1419,0.4218,0.9157,0.7922,0.9595};
      long *indices = IndexSort(testData.size(), &testData[0]);
      for (size_t i = 0; i < testData.size(); ++i )
        cout << testData[indices[i]] << "  has an index of " << indices[i] << "\n";
      delete [] indices;
    }

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