{D,Z}BBCSD: stricter zero criterion #966
Open
Add this suggestion to a batch that can be applied as a single commit.
This suggestion is invalid because no changes were made to the code.
Suggestions cannot be applied while the pull request is closed.
Suggestions cannot be applied while viewing a subset of changes.
Only one suggestion per line can be applied in a batch.
Add this suggestion to a batch that can be applied as a single commit.
Applying suggestions on deleted lines is not supported.
You must change the existing code in this line in order to create a valid suggestion.
Outdated suggestions cannot be applied.
This suggestion has been applied or marked resolved.
Suggestions cannot be applied from pending reviews.
Suggestions cannot be applied on multi-line comments.
Suggestions cannot be applied while the pull request is queued to merge.
Suggestion cannot be applied right now. Please check back later.
Description
The tolerance below which matrix entries are considered zero is tightened to avoid insufficiently accurate singular vectors.
I cannot locate more information about the zero criterion and the choice may be too conservative: there is no information in the git history about it (only the final code was committed in 2010) and in the article Computing the Complete CS Decomposition (2008) from the code author, it only says:
The article Stable Computation of the CS Decomposition: Simultaneous Bidiagonalization does not discuss the zero criterion.
Checklist