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Bug 1455

Summary: LLT::rankUpdate() requires explicit inclusion of Jacobi module
Product: Eigen Reporter: Björn Barz <bjoern.barz>
Component: CholeskyAssignee: Nobody <eigen.nobody>
Severity: Documentation CC: chtz, gael.guennebaud
Priority: Normal    
Version: 3.3 (current stable)   
Hardware: All   
OS: All   

Description Björn Barz 2017-08-04 10:03:43 UTC
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<MatrixXd> llt(A);

        return 0;

This leads to the following compiler errors:

    In file included from /home/barz/lib/eigen-3.3.4/Eigen/Cholesky:31:0,
    /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]’   required from here
    /home/barz/lib/eigen-3.3.4/Eigen/src/Cholesky/LLT.h:254:30: error: ‘Eigen::JacobiRotation<double> g’ has incomplete type
           JacobiRotation<Scalar> 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.
Comment 1 Gael Guennebaud 2017-08-22 09:38:39 UTC
Thank you for the report, fixed: (3.3)
Comment 2 Nobody 2019-12-04 17:07:54 UTC
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