#includeIn this example, we create two vectors v1 and v2, compute their sum, dot product, and cross product, and output the results. The code uses the Vector3d class from the Eigen library and includes the necessary header files. In conclusion, the Vector3d class is a data structure provided by the Eigen library for representing three-dimensional vectors. The library is written in C++ and provides a wide range of linear algebra tools and algorithms.#include using namespace Eigen; int main() { Vector3d v1(1, 2, 3); // create a vector (1, 2, 3) Vector3d v2(4, 5, 6); // create a vector (4, 5, 6) Vector3d v3 = v1 + v2; // add two vectors std::cout << "v3 = " << v3 << std::endl; // output the result double dot = v1.dot(v2); // compute the dot product of two vectors std::cout << "dot = " << dot << std::endl; // output the result Vector3d cross = v1.cross(v2); // compute the cross product of two vectors std::cout << "cross = " << cross << std::endl; // output the result return 0; }