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| #include <Eigen/Core>
| #include <iostream>
| using namespace Eigen;
| using namespace std;
|
| template<typename Derived>
| Eigen::VectorBlock<Derived, 2>
| firstTwo(MatrixBase<Derived>& v)
| {
| return Eigen::VectorBlock<Derived, 2>(v.derived(), 0);
| }
|
| template<typename Derived>
| const Eigen::VectorBlock<const Derived, 2>
| firstTwo(const MatrixBase<Derived>& v)
| {
| return Eigen::VectorBlock<const Derived, 2>(v.derived(), 0);
| }
|
| int main(int, char**)
| {
| Matrix<int,1,6> v; v << 1,2,3,4,5,6;
| cout << firstTwo(4*v) << endl; // calls the const version
| firstTwo(v) *= 2; // calls the non-const version
| cout << "Now the vector v is:" << endl << v << endl;
| return 0;
| }
|
|
