NullPointer exception when trying to fetch eigenvalue

[vsthakur]

I get the following exception when trying to fetch eigenvalue of a symmetric matrix:

Exception in thread "main" java.lang.NullPointerException
at org.ejml.dense.row.decomposition.eig.SymmetricQRAlgorithmDecomposition_DDRM.getEigenvalue(SymmetricQRAlgorithmDecomposition_DDRM.java:118)
at org.ejml.dense.row.decomposition.eig.SwitchingEigenDecomposition_DDRM
.getEigenvalue(SwitchingEigenDecomposition_DDRM.java:74)

Below is my code snippet:
EigenDecomposition_F64 factory = DecompositionFactory_DDRM
.eig(inputDim, true);
DMatrixRMaj covMat = new DMatrixRMaj(covArr);
factory.decompose(covMat);
Double[] eigenVals = new Double[inputDim];
for (int i = 0; i < inputDim; i++) {
eigenVals[i] = factory.getEigenvalue(i).getReal();
}

[lessthanoptimal]

I think you have an imaginary eigenvalue in your dense real matrix. Those are currently not handled. Have a better idea for how to notify the user of the problem?

[vsthakur]

DMatrixRMaj_data.txt
Hi,
PFA the data matrix file. Matrix is symmetric and real. Expect the eigenvalues to be real in this case.
Octave gives real eigenvalues for this matrix.

[lessthanoptimal]

Thanks for the data file. Any chance you can run it through Eigen? I'm planning on revisiting the algorithm used in EJML and curious if their implementation handles it better. I looked at it and I think I know which book they were reading when they implemented it.