#includeIn this example, we create an identity matrix using the `Eigen::Matrix4d::Identity()` method, which returns a matrix of dimensions 4x4 filled with zeros, except for the elements on its main diagonal, which are equal to one. Then, we multiply this matrix by a scalar value to produce a scaled matrix. Eigen is a powerful C++ library for linear algebra and numerical computations. It provides a wide range of functions, including matrix operations, decompositions, solving systems of linear equations, and more. Eigen is open-source software and can be downloaded for free from its website.int main() { // Create an identity matrix with dimensions 4x4 Eigen::Matrix4d identity_matrix = Eigen::Matrix4d::Identity(); // Multiply the identity matrix by a scalar value Eigen::Matrix4d scaled_matrix = 2.0 * identity_matrix; return 0; }