#include#include int main() { Eigen::MatrixXd m(3,3); m << 1,2,3, 4,5,6, 7,8,9; std::cout << "Element at index (1,1): " << m.coeffRef(1,1) << std::endl; return 0; }
#includeIn this example, we create a 3x3 matrix and set its values. We then use the coeffRef function to update the element at the (1,1) index to be 10. We print the original matrix and the updated matrix to see the change. Based on the code examples and the use of the Eigen library, it can be determined that the package library is Eigen.#include int main() { Eigen::MatrixXd m(3,3); m << 1,2,3, 4,5,6, 7,8,9; std::cout << "Original matrix: \n" << m << std::endl; m.coeffRef(1,1) = 10; std::cout << "Updated matrix: \n" << m << std::endl; return 0; }