int nCol = 300;
int nRow = 126;
Eigen::MatrixXf spectrals(nRow, nCol);
spectrals.setOnes();
Eigen::MatrixXf spectrals2(nCol,nRow);
spectrals2.setOnes();
Eigen::MatrixXf mmm = spectrals*spectrals2;
saveMat(mmm, "D:\\mmm.txt");

Environment: VS2012
In the result 'mmm', there are nearly half of the columns are zeros. Is this a bug or something wrong with my code?

Have you double checked the implementation of the saveMat() function? If I replace it by the following code:

Code: Select all

 std::cout << "num of coeffs equal to 300: " << (mmm.array() == 300.0f).count() << std::endl;

I get the expected result:

num of coeffs equal to 300: 15876

benoitsteiner wrote:Have you double checked the implementation of the saveMat() function? If I replace it by the following code:

Code: Select all

 std::cout << "num of coeffs equal to 300: " << (mmm.array() == 300.0f).count() << std::endl;

I get the expected result:

num of coeffs equal to 300: 15876

Thanks for your answer.
I find when I set Eigen::setNbThreads(1); or disable the OpenMP ,the result turned out correct.
As I enabled the OpenMP for my solution, I wonder the parallel multiplication may affect the result.

Which Eigen version are you using? (3.2 or devel branch?)