[eigen] Bug in matrix product with OpenMP?

[Björn Piltz <bjornpiltz@xxxxxxxxxxxxxx>]

Hi all,

I think I just ran into a bug with matrix product and OpenMP. I'm on a MacBook with GCC 4.5.1 and using latest eigen r3481:cb8a3bc8c32b (tip).

The following code fails. Seems like the last half row is filled with garbage.

#include <Eigen/Core>

#include <omp.h>

#include <iostream>

using namespace Eigen;

int main(int argc, char*argv[])

{

	int size = 1529;//Good:1528, Bad:1529

	MatrixXf a = MatrixXf::Random(size, size);

	MatrixXf b = MatrixXf::Random(size, size);

	omp_set_num_threads(1);

	MatrixXf c = a*b;

	omp_set_num_threads(2);

	MatrixXf d = a*b;

	if(!c.isApprox(d))

		std::cerr<<size<<" Error!"<<std::endl;

	return 0;

}

 g++ -I /path/to/eigen -fopenmp -O3 -DNDEBUG product_bug.cpp -o product_bug