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