Re: [eigen] Sparse Matrix Support

[Benoit Jacob <jacob.benoit.1@xxxxxxxxx>]

Here's the way to ping Gael, put him in CC, so gmail puts the email in
this root inbox folder :)

2010/6/17 Keir Mierle <mierle@xxxxxxxxx>:
> Gael, any thoughts? You are the sparse expert.
>
> On Mon, Jun 14, 2010 at 8:25 AM, Sameer Agarwal <sameeragarwal@xxxxxxxxxx>
> wrote:
>>
>> As far as API goes, I think a triplet based constructor like matlab
>> and cholmod provide, where you supply an array of (i,j,s) triplets
>> where M(i,j) =s would be very useful. That way the user can build the
>> matrix in whatever order they want and then just hand over the data to
>> the SparseMatrix constructor.
>>
>> I have used this way of constructing sparse matrices with great
>> success in both c++ and matlab code.
>>
>> In terms of what the libary should support in the short term versus
>> long term,  I would argue for basic BLAS level support for sparse
>> matrices for now before we worry about LAPACK level stuff like
>> solvers. Most people interested in sparse matrices would be more
>> interested in support for various iterative solvers and
>> preconditioners, all of which only require fairly basic operations.
>>
>> For now as long as you offer access to the internal storage of the
>> sparse matrix or allow convenience functions for people to convert
>> that data into something that they can pass to the sparse direct
>> solver of their choice, they are free to call the solver any which way
>> they please.
>>
>> And last but not the least, have you given any thought to supporting
>> block sparse matrices?
>>
>> Sameer
>>
>> On Mon, Jun 14, 2010 at 12:43 AM, Gael Guennebaud
>> <gael.guennebaud@xxxxxxxxx> wrote:
>> > Hi,
>> >
>> > yes the sparse module will be official in Eigen 3.  However it is
>> > still unclear whether it will be considered mature enough to be part
>> > of the 3.0 release, or if it will make it for 3.1 only. The most
>> > realistic is probably a mix of both, i.e., move all the part which are
>> > not fully stable regarding the API to an "unsupported" SparseExtra
>> > module.
>> >
>> > Actually the truth is that I mostly designed the entire module myself
>> > and I don't feel confident enough to consider it API stable. I would
>> > like that more people report on what is cool, what could be improved,
>> > what is missing, etc. Of course patches would be even better, but
>> > feedback on the API would already be of extremely great value :)
>> >
>> > For instance, I don't really like the way the direct solvers are
>> > implemented and made available. This part certainly has to be
>> > redesigned.
>> >
>> > I'm also not sure about the usefulness of the RandomSetters since we
>> > have a dynamic sparse class which is more flexible.
>> >
>> > Last but not least, triangular-ness and selfadjoint-ness is currently
>> > controlled as for dense matrices, i.e., via the selfadjointView and
>> > triangularView. This is needed to maximize the source compatibility
>> > between the two worlds, but for sparse objects which are aimed to be
>> > large, we might also consider runtime flags...
>> >
>> > cheers,
>> >
>> > gael
>> >
>> > On Mon, Jun 14, 2010 at 3:44 AM, Sameer Agarwal
>> > <sameeragarwal@xxxxxxxxxx> wrote:
>> >> Hi Guys,
>> >> I understand that the sparse matrix support in eigen2 was experimental
>> >> and no more bug fixes to it are planned. What is the plan for sparse
>> >> matrix support in eigen3. Is it going to remain an experimental part
>> >> of the library or will it be a fully supported part of it?
>> >>
>> >> Sameer
>> >>
>> >>
>> >>
>> >
>> >
>> >
>>
>>
>
>