Hi,
How can I reconstruct a Matrix with the QR decomposition with Eigen please?
Because there is no method "matrixR()" or "reconstructedMatrix()" in HouseHolderQR, FullPivHouseHolderQR or PartialPivHouseHolderQR.
Thanks.

you are right, they are laking some shortcuts, nevertheless you can do:

MatrixXd r = qr.matrixQR().template triangularView<Upper>();
original = qr.householderQ() * r;

Thanks!