Eigen_eigenvalues_sample.cpp

#include <iostream>
#include "Eigen/Core"
#include "Eigen/Eigenvalues"

int main(void){
  using namespace Eigen;
  Matrix2d A;
  Vector2d a;
  A << 1,-0.5,-0.5,1;
  SelfAdjointEigenSolver<Matrix2d> es(A);
  if(es.info() != Success) std::abort();
  std::cout << es.eigenvalues() << std::endl;

  a = es.eigenvalues();
  double temp0 = a(0);
  double temp1 = a(1);
  std::cout << temp0 << std::endl;
  std::cout << temp1 << std::endl;
  return 0;
}