I have the following

MatrixXd G = some_fun_that_return_MatrixXd();
G.lu();

and I get an error from GCC that says

ndim_fun_obj.cpp:24: error: invalid use of incomplete type ‘const struct Eigen::PartialPivLU<Eigen::Matrix<double, 33331, 33331, 0, 33331, 33331> >’
./Eigen/src/Core/util/ForwardDeclarations.h:153: error: declaration of ‘conststruct Eigen::PartialPivLU<Eigen::Matrix<double, 33331, 33331, 0, 33331, 333

Am I missing something obvious?

#include<Eigen/LU>

Yes, the devel branch needs documentation love...

Now I get the

ndim_fun_obj.cpp:26: error: no matching function for call to ‘Eigen::PartialPivLU<Eigen::Matrix<double, 33331, 33331, 0, 33331, 33331> >::solve(const Eigen:\
:CwiseUnaryOp<Eigen::ei_scalar_opposite_op<double>, Eigen::Matrix<double, 33331, 1, 0, 33331, 1> >, Eigen::VectorXd**) const’

I have

#include<Eigen/LU>
#include<Eigen/Core>
using namespace Eigen;

How is the namespace managed? Are they all under Eigen?

the new solve() API is: result = lu.solve(right_hand_side)

Thank you... my stupidity for not looking at the right doc