Good day,

I currently have code that uses std::vectors and am new to Eigen. Could you please inform me on how to typecast these std::vectors to Eigen::VectorXd? I don't want a copy of the data in the std::vector to be made. So far, I've only seen the 'Map' function but that maps arrays and not vectors.

Thank You

You can use Map for any kind of dense objects, like vectors.

VectorXf::Map(pointer, size)

Thanks. I figured it out. I was supposed to create a pointer to the vector as follows.


std::vector<double> v(4, 100.0);
double* ptr = &v[0];
Eigen::Map<Eigen::VectorXd> my_vect(ptr, 4);

Is their a way to get to Eigen::VectorXd to std::vector<double> ? I searched the internet but all in vain till now. May be its something very basic.

I guess this is a cross-post, so for the record: http://stackoverflow.com/questions/2609 ... -stdvector

Hi,

Sorry to dredge up an old post but my issue is related.

I am trying to convert a std::vector of complex doubles to a VectorXcd but am getting the error: "YOU_MIXED_DIFFERENT_NUMERIC_TYPES__YOU_NEED_TO_USE_THE_CAST_METHOD_OF_MATRIXBASE_TO_CAST_NUMERIC_TYPES_EXPLICITLY"

As far as I can tell the scalar type should both be complex doubles? Here is my code:

VectorXcd v3 = VectorXcd::Map(&v2[10], v2.size());

I also tried Map<VectorXcd>v3(&v2[0], v2.size());

Thanks,

Kris

Your problem is probably somewhere else. Here is a self-contained working example:

Code: Select all

#include <Eigen/Dense>
#include <vector>
using namespace Eigen;
int main() {
  std::vector<std::complex<double> > v2(10);
  VectorXcd v3 = VectorXcd::Map(v2.data(), v2.size());
}


ggael wrote:Your problem is probably somewhere else. Here is a self-contained working example:

Code: Select all

#include <Eigen/Dense>
#include <vector>
using namespace Eigen;
int main() {
  std::vector<std::complex<double> > v2(10);
  VectorXcd v3 = VectorXcd::Map(v2.data(), v2.size());
}


Thanks for this! I got it sorted, you were right it was related to an issue elsewhere in my code.