About PZHEEVX

[hxdeng]

I am a novice for scalapack and sincerely hope get some help. Recently I
try to solve the eigen values and eigenvectors of a 8200x8200 complex matrix
using the subroutine PZHEEVX. But I get the return INFO=2. If successful exit,
the subroutine PZHEEVX should give INF0=0.I find the eigen values are correct
even when INFO=2.I don't know whether all of the eigenvectors are correct. Does that INFO=2 affect the
calculating eigen values and eigenvectors? What can I do to correct the error report?
Thank you very much.

[Julien Langou]

I am not an expert for using this routine but if INFO = 2 then you are in the case " (MOD(INFO/2,2).NE.0) " therefore:

* if (MOD(INFO/2,2).NE.0),then eigenvectors corresponding
* to one or more clusters of eigenvalues could not be
* reorthogonalized because of insufficient workspace.
* The indices of the clusters are stored in the array
* ICLUSTR.

In clear this means that PZHEEVX does not guarantee that the matrix of eigenvectors V has orthonormal columns.
I do not exactly know what you should do. Maybe increase the workspace? If you need all the eigenvalues/eigenvectors,
you might want to try PZHEEVD?