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fix a numerical issue in the direct 3x3 eigenvector extraction

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This commit is contained in:
Gael Guennebaud 2011-08-08 10:46:26 +02:00
parent a660e6425c
commit f162f7c323
1 changed files with 10 additions and 3 deletions
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11
Eigen/src/Eigenvalues/SelfAdjointEigenSolver.h
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@ -554,6 +554,7 @@ template<typename SolverType> struct direct_selfadjoint_eigenvalues<SolverType,3
inline static void run(SolverType& solver, const MatrixType& mat, int options)
{
using std::sqrt;
eigen_assert(mat.cols() == 3 && mat.cols() == mat.rows());
eigen_assert((options&~(EigVecMask|GenEigMask))==0
&& (options&EigVecMask)!=EigVecMask
@ -584,7 +585,14 @@ template<typename SolverType> struct direct_selfadjoint_eigenvalues<SolverType,3
MatrixType tmp;
tmp = scaledMat;
tmp.diagonal().array () -= eivals(2);
eivecs.col(2) = tmp.row(0).cross(tmp.row(1)).normalized();
VectorType cross01 = tmp.row(0).cross(tmp.row(1));
VectorType cross02 = tmp.row(0).cross(tmp.row(2));
Scalar n01 = cross01.squaredNorm();
Scalar n02 = cross02.squaredNorm();
if(n01>n02)
eivecs.col(2) = cross01 / sqrt(n01);
else
eivecs.col(2) = cross02 / sqrt(n02);
tmp = scaledMat;
tmp.diagonal().array() -= eivals(1);
@ -600,7 +608,6 @@ template<typename SolverType> struct direct_selfadjoint_eigenvalues<SolverType,3
eivecs.col(0) = eivecs.col(2).cross(eivecs.col(1));
}
}
// Rescale back to the original size.
eivals *= scale;