don't subtract N_DEFLATED from istop twice #794
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Description
closes #793
During AED, eigenvalues of a subblock are calculated, some of these are deflated, others are stored to be used as shifts during the next multishift QZ iteration.
The shifts are stored in the eigenvalue array at an index corresponding to the top of the AED window. This equals
istop - nd - ns + 1. However, after the AED call,istopis set toistop - ndto reflect the new active window. This means that the shifts are now stored at indexistop - ns + 1.This issue was not detected before, because usually, when
ndis large enough that a significant amount of wrong shifts would be used, we skip the sweep in favor of doing another AED step.Checklist