CODEWITHSUNDEEP
c++eigen
Korchkidu
Korchkidu

Reputation: 4946

Force Eigen to check matrices dimensions at run-time

It seems that Eigen does not check dynamic matrices dimensions. For example, if I execute the following code:

auto EA = Eigen::MatrixXf(3, 2);
auto EB = Eigen::MatrixXf(3, 2);
for (auto i = 0; i < 3; ++i)
{
  for (auto j = 0; j < 2; ++j)
  {
    EA(i,j) = i + j + 1;
    EB(i,j) = i + j + 1;
  }
}
auto EC = EA*EB;
std::cout << "EA: " << std::endl << EA << std::endl;
std::cout << "EB: " << std::endl << EB << std::endl;
std::cout << "EC: " << std::endl << EC << std::endl;

It outputs:

EA:
1 3
2 3
2 4
EB:
1 3
2 3
2 4
EC:
 7 12
 8 15
10 18

How do I force Eigen to check matrices dimensions at run-time? This would be really useful for beginners and for debugging.

Upvotes: 0

Views: 528

Answers (1)

Ruslan
Ruslan

Reputation: 19130

Dimension checking only happens when NDEBUG macro is not defined. This normally means a debug build.

Example without NDEBUG, where the checks successfully abort the program:

g++ test.cpp -o test -I /usr/include/eigen3 && ./test
test: /usr/include/eigen3/Eigen/src/Core/ProductBase.h:102: Eigen::ProductBase<Derived, Lhs, Rhs>::ProductBase(const Lhs&, const Rhs&) [with Derived = Eigen::GeneralProduct<Eigen::Matrix<float, -1, -1>, Eigen::Matrix<float, -1, -1>, 5>; Lhs = Eigen::Matrix<float, -1, -1>; Rhs = Eigen::Matrix<float, -1, -1>]: Assertion `a_lhs.cols() == a_rhs.rows() && "invalid matrix product" && "if you wanted a coeff-wise or a dot product use the respective explicit functions"' failed.
Aborted (core dumped)

And with NDEBUG:

g++ test.cpp -o test -I /usr/include/eigen3 -DNDEBUG && ./test
EA: 
1 2
2 3
3 4
EB: 
1 2
2 3
3 4
EC: 
 5  8
 8 13
11 18

Upvotes: 3

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