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Dec 21, 2016 at 21:39 comment added Jeff Yes, adding $cI$ and doing inverse iterations works well.
Dec 20, 2016 at 18:49 comment added VF1 @Jeff have you tried this? I am having the same issue. Is it better Lanczos? It also seems that the Gershgorin bound would be a quickly-computable always-valid value for $c$.
Aug 27, 2012 at 17:08 vote accept Jeff
Aug 25, 2012 at 1:52 comment added Igor Rivin You don't need a representation of $M^{-1},$ you just need to iterate $M^{-1}$ on some random starting vector, which is what you do with conjugate gradient, so this requires no storage.
Aug 24, 2012 at 23:52 comment added Jeff Thanks for the response. So you're proposing I 1) set $M=cI + D - AA'$, 2) solve for $M^{-1}$ with conjugate gradient, and 3) find the eigenvector corresponding to the second largest eigenvalue of $M^{-1}$? I like the use of ridging -- I had forgotten about that technique. But, one concern: Since $M$ isn't sparse, won't conjugate gradient produce a representation of $M^{-1}$ that is too large to fit into memory?
Aug 24, 2012 at 21:49 history answered Igor Rivin CC BY-SA 3.0