Eigen - Re-orthogonalization of Rotation Matrix

Question

After multiplying a lot of rotation matrices, the end result might not be a valid rotation matrix any more, due to rounding issues (de-orthogonalized)

One way to re-

Answer 1

In the meantime:

#include 

Eigen::Matrix3d mmm;
Eigen::Matrix3d rrr;
                rrr <<  0.882966, -0.321461,  0.342102,
                        0.431433,  0.842929, -0.321461,
                       -0.185031,  0.431433,  0.882966;
                     // replace this with any rotation matrix

mmm = rrr;

Eigen::AngleAxisd aa(rrr);    // RotationMatrix to AxisAngle
rrr = aa.toRotationMatrix();  // AxisAngle      to RotationMatrix

std::cout <<     mmm << std::endl << std::endl;
std::cout << rrr     << std::endl << std::endl;
std::cout << rrr-mmm << std::endl << std::endl;

Which is nice news, because I can get rid of my custom method and have one headache less (how can one be sure that he takes care of all singularities?),

but I really want your opinion on better/alternative ways :)