Clustering sometimes crashes JPlag

[uuqjz]

The default clustering method of JPlag is SpectralClustering, which uses org.apache.commons.math3.linear.EigenDecomposition for the eigenvalue decomposition.

EigenDecomposition has a hard-coded limit for the number of iterations until the algorithm must converge or it throws an unhandled MaxCountExceededException.
The limit is set to 30 and as a private field without a setter cannot be changed:
private byte maxIter = 30;

This results in JPlag sometimes crashing when the eigenvalue decomposition doesn't converge.

[tsaglam]

Right now, this only occurs when using match merging, right?

[uuqjz]

Right now, this only occurs when using match merging, right?

Yes, I only noticed it when using match merging

[SimDing]

When I implemented the spectral clustering I thought that the eigendecomposition should always work on real symmetric matrices (Spectral Theorem), and the Laplacian matrix in SpectralClustering.java is symmetric by construction. Therefore I did not catch that exception...
I can not reproduce this. Maybe numerical errors cause this? We could try to set very small entries in the Laplacian to zero. Like any value $x$ with $|x| < eps * ||L||_F /n^2$.