Copy data from std::vector to Eigen's MatrixXd in C++ -

eigen linear algebra library in c++. have data (double type) in std::vector (datavector in code below) type array. try copy row-wise using following code still giving results column-wise.

map<matrixxd, rowmajor> mymatrix(datavector.data(), m, n); 

am doing correct syntax here?

no. matrixxd object has defined row/column major. see example below.

#include <eigen/core> #include <iostream> #include <vector>  using std::cout; using std::endl;  int main(int argc, char *argv[]) {     std::vector<int> dat(4);     int = 0;     dat[i] = + 1; i++;     dat[i] = + 1; i++;     dat[i] = + 1; i++;     dat[i] = + 1;     typedef eigen::matrix<int, -1, -1, eigen::colmajor> cm;     eigen::map<cm> m1(dat.data(), 2, 2);     cout << m1 << endl << endl;      typedef eigen::matrix<int, -1, -1, eigen::rowmajor> rm;     eigen::map<rm> m2(dat.data(), 2, 2);     cout << m2 << endl << endl;      return 0; } 

outputs:

1 3 2 4  1 2 3 4