How to get the number of rows and columns of an Eigen::MatrixXd?

Question

I am trying to traverse Eigen::MatrixXd matrix. However, there does not seem to be a function that returns the columns size nor the row size. Does anybody have an idea on how to do this?

Answer 1

This should work...

#include <Eigen/Dense>

int main()
{
    Eigen::MatrixXd matrix(3, 4);

    int r = matrix.rows();
    int c = matrix.cols();

    for (int i = 0; i < r; ++i)
    {
        for (int j = 0; j < c; ++j)
        {
            std::cout << matrix(i,j) << " ";
        }
        std::cout << std::endl;
    }

    return 0;
}