IIRC it was in fact you who suggested using not a plain packed but a rectangular full packed format ;-) (https://software.intel.com/content/www/us/en/develop/documentation/mkl-developer-reference-c/top/lapack-routines/matrix-storage-schemes-for-lapack-routines.html#matrix-storage-schemes-for-lapack-routines_RFP_STORAGE <https://software.intel.com/content/www/us/en/develop/documentation/mkl-developer-reference-c/top/lapack-routines/matrix-storage-schemes-for-lapack-routines.html#matrix-storage-schemes-for-lapack-routines_RFP_STORAGE>)
If this is worth definitely depends on the particular use-case. It has been shown that a rectangular full packed format can be beneficial for e.g. Cholesky (http://www.netlib.org/lapack/lawnspdf/lawn199.pdf <http://citeseerx.ist.psu.edu/viewdoc/download?doi=10.1.1.214.102&rep=rep1&type=pdf>) or Pade approximations (https://pdfs.semanticscholar.org/86d2/28da4fc02672b2c990eb48a5a605c0e0360f.pdf <https://pdfs.semanticscholar.org/86d2/28da4fc02672b2c990eb48a5a605c0e0360f.pdf>). I published benchmark on this list and will try to dig them out. A Hermitian*Hermitian product can be quite fast (you can basically fall back to gemm for blocks in the RFP format) but Dense*Hermitian was not so good if I remember correctly. David > On 6. Oct 2020, at 02:16, Rasmus Munk Larsen <[email protected]> wrote: > > David, > > I can see that this might save 50% of memory by only storing the upper or > lower triangle, and it would be nice to be able to automatically dispatch to > faster eigensolvers etc. for Hermitian matrices. However, packed storage > kernels are notoriously hard to optimize, and I wonder how much we would gain > over the existing mechanism like SelfAdjointView? > > https://eigen.tuxfamily.org/dox/classEigen_1_1SelfAdjointView.html\ > <https://eigen.tuxfamily.org/dox/classEigen_1_1SelfAdjointView.html/> > > Do you have some benchmark numbers for your patch? > > Rasmus > > On Mon, Oct 5, 2020 at 5:07 PM David Tellenbach > <[email protected] <mailto:[email protected]>> > wrote: > Hi Jens, > > It would be great if you could finish this! I just saw that the patch is not > accessible anymore, I'll see if I can find it. > > Best, > David > >> On 4. Oct 2020, at 21:27, Jens Wehner <[email protected] >> <mailto:[email protected]>> wrote: >> >> Thanks David, >> >> I would probably like to give it a shot to brush up on my template >> programming skills or lack thereof. >> >> Do you have the code somewhere public so I can have a look? If you have time >> afterwards we can have a chat about the better implementation. >> >> Cheers Jens >> >> | Jens Wehner, PhD | eScience Research Engineer | Email: >> [email protected] >> <https://outlook.office.com/mail/options/mail/[email protected]> | >> Tel: +31(0)6 438 666 87 | >> | Netherlands eScience Center <https://www.esciencecenter.nl/> | Science >> Park 140 | 1098 XG Amsterdam | The Netherlands | >> | Twitter <https://twitter.com/eScienceCenter> | LinkedIn >> <https://www.linkedin.com/company/netherlands-escience-center> | Facebook >> <https://www.facebook.com/NLeScienceCenter/> | YouTube >> <https://www.youtube.com/channel/UCYLAIMi62d8tx3Ru6DOSPeg> | Newsletter >> <https://esciencecenter.us8.list-manage.com/subscribe/post?u=a0a563ca342f1949246a9f92f&id=31bfc2303d> >> | >> >> >> From: David Tellenbach <[email protected] >> <mailto:[email protected]>> >> Sent: Sunday, October 4, 2020 0:16 >> To: [email protected] <mailto:[email protected]> >> <[email protected] <mailto:[email protected]>> >> Subject: Re: [eigen] Hermitian matrices >> >> Hi Jens, >> >> Yes, I've implemented support for Hermitian matrices as a Google Summer of >> Code student in 2018 and finishing it is still somewhere on my backlog. >> However, with today's knowledge the implementation should look quite >> differently. If you are interested to work on this I'm happy to discuss. >> Otherwise you will have to wait until I find some time to reimplement it. >> This won't take me too long but without committing to anything, I can >> already say that I won't find time before the beginning of 2021. >> >> Best, >> David >> >>> On 2. Oct 2020, at 23:30, Jens Wehner <[email protected] >>> <mailto:[email protected]>> wrote: >>> >>> I recently discovered that David Tellenbach started/was in the >>> middle/finished a >>> >>> Hermitian matrix class. >>> http://manao.inria.fr/eigen_tmp/pullrequests/467/ >>> <http://manao.inria.fr/eigen_tmp/pullrequests/467/> >>> I wanted to know what the status is and if any help is needed to push that >>> along. >>> >>> Cheers Jens >>> | Jens Wehner, PhD | eScience Research Engineer | Email: >>> [email protected] >>> <https://outlook.office.com/mail/options/mail/[email protected]> | >>> Tel: +31(0)6 438 666 87 | >>> | Netherlands eScience Center <https://www.esciencecenter.nl/> | Science >>> Park 140 | 1098 XG Amsterdam | The Netherlands | >>> | Twitter <https://twitter.com/eScienceCenter> | LinkedIn >>> <https://www.linkedin.com/company/netherlands-escience-center> | Facebook >>> <https://www.facebook.com/NLeScienceCenter/> | YouTube >>> <https://www.youtube.com/channel/UCYLAIMi62d8tx3Ru6DOSPeg> | Newsletter >>> <https://esciencecenter.us8.list-manage.com/subscribe/post?u=a0a563ca342f1949246a9f92f&id=31bfc2303d> >>> | >
