| Brian Silverman | 72890c2 | 2015-09-19 14:37:37 -0400 | [diff] [blame] | 1 | #include <Eigen/Core> |
| 2 | #include <iostream> |
| 3 | using namespace Eigen; |
| 4 | using namespace std; |
| 5 | |
| 6 | template<typename Derived> |
| 7 | Eigen::VectorBlock<Derived, 2> |
| 8 | firstTwo(MatrixBase<Derived>& v) |
| 9 | { |
| 10 | return Eigen::VectorBlock<Derived, 2>(v.derived(), 0); |
| 11 | } |
| 12 | |
| 13 | template<typename Derived> |
| 14 | const Eigen::VectorBlock<const Derived, 2> |
| 15 | firstTwo(const MatrixBase<Derived>& v) |
| 16 | { |
| 17 | return Eigen::VectorBlock<const Derived, 2>(v.derived(), 0); |
| 18 | } |
| 19 | |
| 20 | int main(int, char**) |
| 21 | { |
| 22 | Matrix<int,1,6> v; v << 1,2,3,4,5,6; |
| 23 | cout << firstTwo(4*v) << endl; // calls the const version |
| 24 | firstTwo(v) *= 2; // calls the non-const version |
| 25 | cout << "Now the vector v is:" << endl << v << endl; |
| 26 | return 0; |
| 27 | } |