Re: [eigen] Iterators with dense matrices: (was: Areas of eigen3 variation and using eigen2/3 in generic code)

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

Hi,

Thanks for sharing all these thoughts. I put a few comments below.

Later today I will do the renaming, making it possible to add proper
iterators support with begin()/end(). But, as Hauke mentions, we are
currently in a rush to prepare Eigen 3.0 and we can't afford to
prioritize iterators at the moment. Also, as I mentioned above, once
this renaming is done, nothing prevents you from adding iterators
yourself, even without patching eigen at all:

http://eigen.tuxfamily.org/dox/CustomizingEigen.html#ExtendingMatrixBase

2010/1/4 Jesse Perla <jesseperla@xxxxxxxxx>:
> 3) Cursors for Sparse Matrices
> This is getting above my pay grade... I hope Paul or someone who does a lot
> of sparse algorithms can correct it.
> Where cursors/iterators are essential is with sparse algorithms.  The reason
> is that you need to go through only the non-zero elements.

We already have this, Gael who wrote the Sparse module based it
completely on iterators.

> 4) Iterators for Matrices and Tensors
> Assuming that Eigen moves towards having multidimensional structures,

In fact, Eigen is completely specialized to 1D (Vectors) and 2D
(matrices). Given how hard the 2D case already is to optimize, and
given how convenient it is to be able to completely specialize the API
on these cases, we don't plan to support higher-dimensional arrays.

Benoit