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- To: eigen@xxxxxxxxxxxxxxxxxxx
- Subject: Re: [eigen] Diagonal matrices diff
- From: Gael Guennebaud <gael.guennebaud@xxxxxxxxx>
- Date: Sun, 10 May 2009 16:22:02 +0200
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Hi,
I did not read your patch carefully (no time right now) but initially
I thought it would be better to keep DiagonalCoeffs and add a new Band
class (for compilation time, more specialized API, etc...).
see what I wrote:
http://eigen.tuxfamily.org/index.php?title=SpecialMatrix#skyline.2Fband_matrix
Also I don't understand how your patch works. The former
DiagonalCoeffs class is able to represent any sub/super diagonal but
that's it, and I don't see where is the extra parameter allowing to
represent a band, i.e., a set of sub/super diagonal....
more comments when I'll more time...
Gael.
On Sat, May 9, 2009 at 6:17 AM, Benoit Jacob <jacob.benoit.1@xxxxxxxxx> wrote:
> Hi,
>
> before i can do the svd i need Banded matrices, for which i needed
> some improvements in DiagonalCoeffs.
> So here's a patch but as it is changing several things i thought i'd
> ask for your opinion (you know who you are) before committing.
> * rename DiagonalCoeffs (clumsy name) to Band. I tried first Diagonal,
> but that name was already taken by a constant Diagonal which is used
> for various things already.
> * rename the template parameter DiagId to Index.
> * keep diagonal() unchanged, returns a Band<Derived, 0>
> * rename diagonal<int>() to band<int>()
> * introduce diagonal(int), returning a Band<Derived, Dynamic>. The
> trick here is as we already do in Block : use ei_int_if_dynamic to
> store the Index in Band.
> ---> that is the improvement that i need in order to code
> BandedMatrix. No need to unroll an outer loop there, and that also
> will reduce compilation times (only one Band type instantiated).
>
> Cheers,
> Benoit
>