#includeusing namespace Eigen; int main() { Matrix matrix; std::cout << "Matrix has " << matrix.cols() << " columns" << std::endl; return 0; }
#includeIn this example, we create a vector with 3 elements. We then use the cols function to print the number of columns in the vector. Package Library: Eigen is an open-source C++ library that provides linear algebra operations for matrices and vectors.using namespace Eigen; int main() { VectorXd vec(3); std::cout << "Vector has " << vec.cols() << " columns" << std::endl; return 0; }