threed-beam-fea/ext/eigen-3.3.4/doc/examples/function_taking_ref.cpp

20 lines
594 B
C++

#include <iostream>
#include <Eigen/SVD>
using namespace Eigen;
using namespace std;
float inv_cond(const Ref<const MatrixXf>& a)
{
const VectorXf sing_vals = a.jacobiSvd().singularValues();
return sing_vals(sing_vals.size()-1) / sing_vals(0);
}
int main()
{
Matrix4f m = Matrix4f::Random();
cout << "matrix m:" << endl << m << endl << endl;
cout << "inv_cond(m): " << inv_cond(m) << endl;
cout << "inv_cond(m(1:3,1:3)): " << inv_cond(m.topLeftCorner(3,3)) << endl;
cout << "inv_cond(m+I): " << inv_cond(m+Matrix4f::Identity()) << endl;
}