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[Lapack] INFO=N+2 in xDGGES

Dear lapack developers,

I believe I found a minor little small bug in xDGGES, which should return
info=n+3 if xTGSEN fails to swap eigenvalues at all, and return info=n+2 if
swapping slightly changes eigenvalues so that the selected eigenvalues are
not only in the upper part.

I am referening to dgges.f in lapack 3.2.1 which i downloaded recently.

Indeed, on line 444 the routine sets info=n+3 upon error in dtgsen. However,
then it checks whether the selected eigenvalues are only in the upper part.
If dtgsen has failed, it is almost certain that it is the case that the
selected eigenvalues are not only in the upper part, and info=n+2 is set. In
this way user does not get info=n+3, but only info=n+2.

Many thanks for your great job.

Ondra K.
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