LLT::rankUpdate() requires explicit inclusion of Jacobi module

Submitted by Björn Barz

Assigned to Nobody

Link to original bugzilla bug (#1455)
Version: 3.3 (current stable)

Description

The LLT::rankUpdate() method apparently requires the Jacobi module. This requirement is not documented anywhere and straightforward use of the method without explicitly including Eigen/Jacobi leads to compiler errors.

For example, trying to compile the following code:

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

int main(int argc, char * argv[])  
{  
    MatrixXd A = MatrixXd::Random(10, 10);  
    A = A * A.transpose();  
    VectorXd v = VectorXd::Random(10);  

    LLT&lt;MatrixXd&gt; llt(A);  
    llt.rankUpdate(v);  

    return 0;  
}  

This leads to the following compiler errors:

In file included from /home/barz/lib/eigen-3.3.4/Eigen/Cholesky:31:0,  
                 from eigen_test.cc:2:  
/home/barz/lib/eigen-3.3.4/Eigen/src/Cholesky/LLT.h: In instantiation of ‘Eigen::Index Eigen::internal::llt_rank_update_lower(MatrixType&, const VectorType&, const typename MatrixType::RealScalar&) [with MatrixType = Eigen::Matrix<double, -1, -1>; VectorType = Eigen::Matrix<double, -1, 1>; Eigen::Index = long int; typename MatrixType::RealScalar = double]’:  
/home/barz/lib/eigen-3.3.4/Eigen/src/Cholesky/LLT.h:362:66:   required from ‘static Eigen::Index Eigen::internal::llt_inplace<Scalar, 1>::rankUpdate(MatrixType&, const VectorType&, const RealScalar&) [with MatrixType = Eigen::Matrix<double, -1, -1>; VectorType = Eigen::Matrix<double, -1, 1>; Scalar = double; Eigen::Index = long int; Eigen::internal::llt_inplace<Scalar, 1>::RealScalar = double]’  
/home/barz/lib/eigen-3.3.4/Eigen/src/Cholesky/LLT.h:462:91:   required from ‘Eigen::LLT<MatrixType, _UpLo> Eigen::LLT<MatrixType, UpLo>::rankUpdate(const VectorType&, const RealScalar&) [with VectorType = Eigen::Matrix<double, -1, 1>; _MatrixType = Eigen::Matrix<double, -1, -1>; int _UpLo = 1; Eigen::LLT<MatrixType, UpLo>::RealScalar = double]’  
eigen_test.cc:12:21:   required from here  
/home/barz/lib/eigen-3.3.4/Eigen/src/Cholesky/LLT.h:254:30: error: ‘Eigen::JacobiRotation&lt;double&gt; g’ has incomplete type  
       JacobiRotation&lt;Scalar&gt; g;  
                              ^  
/home/barz/lib/eigen-3.3.4/Eigen/src/Cholesky/LLT.h:262:44: error: ‘apply_rotation_in_the_plane’ was not declared in this scope  
         apply_rotation_in_the_plane(x, y, g);  
                                            ^  

Adding "#include <Eigen/Jacobi>" solves this.
This requirement should either be documented or resolved implicitly.