ground/gcs/src/libs/eigen/doc/examples/function_taking_ref.cpp

   1 #include <iostream>
   2 #include <Eigen/SVD>
   3 using namespace Eigen;
   4 using namespace std;
   5
   6 float inv_cond(const Ref<const MatrixXf>& a)
   7 {
   8   const VectorXf sing_vals = a.jacobiSvd().singularValues();
   9   return sing_vals(sing_vals.size()-1) / sing_vals(0);
  10 }
  11
  12 int main()
  13 {
  14   Matrix4f m = Matrix4f::Random();
  15   cout << "matrix m:" << endl << m << endl << endl;
  16   cout << "inv_cond(m):          " << inv_cond(m)                      << endl;
  17   cout << "inv_cond(m(1:3,1:3)): " << inv_cond(m.topLeftCorner(3,3))   << endl;
  18   cout << "inv_cond(m+I):        " << inv_cond(m+Matrix4f::Identity()) << endl;
  19 }