Get matrix views/blocks from a Eigen::VectorXd without copying (shared memory)

Question

Does anyone know a good way how i can extract blocks from an Eigen::VectorXf that can be interpreted as a specific Eigen::MatrixXf without copying data? (the vector should c

Answer 1

If you want to reinterpret a subvector as a matrix then yes, you have to use Map:

Map<Matrix2d> A(W.data());          // using the first 4 elements
Map<Matrix2d> B(W.tail(4).data());  // using the last 4 elements
Map<MatrixXd> C(W.data()+6, 2,2);   // using the 6th to 10th elements
                                    // with sizes defined at runtime.