1 #include <Eigen/Core>
2 #include <iostream>
3 using namespace Eigen;
4 using namespace std;
5
6 template<typename Derived>
7 Eigen::VectorBlock<Derived>
segmentFromRange(MatrixBase<Derived> & v,int start,int end)8 segmentFromRange(MatrixBase<Derived>& v, int start, int end)
9 {
10 return Eigen::VectorBlock<Derived>(v.derived(), start, end-start);
11 }
12
13 template<typename Derived>
14 const Eigen::VectorBlock<const Derived>
segmentFromRange(const MatrixBase<Derived> & v,int start,int end)15 segmentFromRange(const MatrixBase<Derived>& v, int start, int end)
16 {
17 return Eigen::VectorBlock<const Derived>(v.derived(), start, end-start);
18 }
19
main(int,char **)20 int main(int, char**)
21 {
22 Matrix<int,1,6> v; v << 1,2,3,4,5,6;
23 cout << segmentFromRange(2*v, 2, 4) << endl; // calls the const version
24 segmentFromRange(v, 1, 3) *= 5; // calls the non-const version
25 cout << "Now the vector v is:" << endl << v << endl;
26 return 0;
27 }
28